C.I.A. Director Is Heading to Cairo for New Truce Talks

“President Biden emphasized that the strikes on humanitarian workers and the overall humanitarian situation are unacceptable,” according to a White House summary of the call. “He made clear the need for Israel to announce and implement a series of specific, concrete, and measurable steps to address civilian harm, humanitarian suffering, and the safety of aid workers. He made clear that U.S. policy with respect to Gaza will be determined by our assessment of Israel’s immediate action on these steps.”

The statement was the sharpest the White House has issued on Israel’s conduct in the six months of its war against Hamas, underscoring the president’s growing frustration with Mr. Netanyahu and his anger over this week’s killing of seven aid workers by Israeli military forces. But while the president repeated his call for a negotiated deal that would result in an “immediate cease-fire” and the release of hostages taken by Hamas, White House officials stopped short of saying directly that he might limit U.S. arms supplies if not satisfied.

By the middle of the night in Jerusalem, Israel made its first gestures to Mr. Biden. In a statement, a spokeswoman for the U.S. National Security Council said Israel had agreed to use the Ashdod port to direct aid into Gaza, to open the Erez crossing into northern Gaza for the first time since the Hamas terrorist attack on Oct. 7, and to significantly increase deliveries from Jordan.

Biden administration officials, who spoke on the condition of anonymity to describe the private call in more detail, said that Mr. Netanyahu agreed to additional commitments intended to assuage the president. Among others, the officials said, Israel would promise to institute more measures to reduce civilian casualties and to empower negotiators brokering a temporary cease-fire deal in exchange for the release of hostages.

The reported agreement came as American officials held out the prospect of consequences if Mr. Netanyahu resisted. Secretary of State Antony J. Blinken, who dialed into the call between the president and prime minister, said afterward that Israel needed to do more to increase the flow of humanitarian supplies to Gaza, a challenge that has expanded exponentially since the attack on aid workers prompted some groups to reconsider their activities on the ground.

“If we lose that reverence for human life, we risk becoming indistinguishable from those we confront,” Mr. Blinken said during a stop at NATO headquarters in Brussels. “Here’s the current reality in Gaza despite important steps that Israel has taken to allow assistance into Gaza: The results on the ground are woefully insufficient and unacceptable.”

The secretary of state made clear that the Biden administration was now ready to exact a price if Israel continued to rebuff its counsel. “If we don’t see the changes that we need to see, there’ll be changes in policy,” he said.

The president has long refused to curb the arms flow to influence Israel’s approach to the war. Mr. Biden said after Hamas killed 1,200 people and took hundreds of hostages in October that his support for Israel was “rock solid and unwavering.” While he has increasingly criticized what he sees as the excesses of the military operation, he has until now stuck by his vow.

But with rising agitation on the political left, particularly in electoral swing states like Michigan, even some of Mr. Biden’s closest Democratic allies are coming around to the view that Washington should exercise more control over the weaponry, including Senator Chris Coons, a fellow Democrat from Delaware and confidant of the president.

“I think we’re at that point,” Mr. Coons said on CNN on Thursday morning. If Mr. Netanyahu were to order the Israeli military into the southern Gaza city of Rafah in force and “drop thousand-pound bombs and send in a battalion to go after Hamas and make no provision for civilians or for humanitarian aid,” he added, then “I would vote to condition aid to Israel.”

Mr. Netanyahu did not immediately release a description of his call with Mr. Biden, but in other comments on Thursday he appeared unbowed. In a meeting in Jerusalem with visiting Republican lawmakers organized by the American Israel Public Affairs Committee, known as AIPAC, the prime minister pushed back strongly against Mr. Biden’s longstanding insistence on a two-state solution to the Palestinian conflict.

“There is a contrary move, an attempt to force, ram down our throats a Palestinian state, which will be another terror haven, another launching ground for an attempt, as was the Hamas state in Gaza,” Mr. Netanyahu said. “That is opposed by Israelis, overwhelmingly.”

In a separate video statement, he focused on the threat he sees from Iran. “For years, Iran has been acting against us, both directly and through its proxies, and therefore Israel is acting against Iran and its proxies, in both defensive and offensive operations,” Mr. Netanyahu said, referring to an Israeli airstrike that killed seven Iranian military officers in Syria this week.

“We will know how to defend ourselves,” he added, “and we will operate according to the simple principle by which those who attack us or plan to attack us — we will attack them.”

The White House statement noted that Mr. Biden stood by Israel against Iran during his Thursday call with Mr. Netanyahu, which in addition to Mr. Blinken included Vice President Kamala Harris and Jake Sullivan, the national security adviser.

“The two leaders also discussed public Iranian threats against Israel and the Israeli people,” the statement said. “President Biden made clear that the United States strongly supports Israel in the face of those threats.”

Unlike previous comments, however, the latest White House statement made no mention of Oct. 7 nor the by-now ritual defense of Israel’s right to respond to Hamas. Instead, it emphasized that “an immediate cease-fire is essential” and said that Mr. Biden “urged the prime minister to empower his negotiators to conclude a deal without delay to bring the hostages home.” A person briefed on the situation, who spoke on the condition of anonymity, said negotiators including William J. Burns, the C.I.A. director, will travel to Cairo on Saturday for further talks on such a deal.

At a briefing after the call between the leaders, John F. Kirby, a White House spokesman, said the president wants to see “concrete tangible steps” to reduce the violence against civilians and increase access for humanitarian aid to Gaza and predicted that Israel would make announcements of specific changes within hours or days.

But Mr. Kirby would not outline specific metrics for judging Israel’s response or what Mr. Biden would do if not satisfied. “What we want to see are some real changes on the Israeli side and, you know, if we don’t see changes from their side, there will have to be changes from our side,” he said.

Some Israel supporters criticized Mr. Biden for giving in to pressure from the left, arguing that it could prolong the war by emboldening Israel’s enemies. “Hamas, Iran, Hezbollah, and the rest of the destroy-Israel axis are sitting back and reveling in the growing tensions and signs of a coming breach between Washington and Jerusalem,” said John Hannah, a senior fellow at the Jewish Institute for National Security of America.

The pivot stemmed from the killing of the seven aid workers, who were deployed in Gaza by World Central Kitchen, the humanitarian group founded by the celebrity chef José Andrés. Mr. Biden called himself “outraged and heartbroken” over the incident and made a point of calling Mr. Andrés to express his condolences.

The seven workers were killed by three successive strikes on three cars traveling along a road in Gaza. Israeli officials have called the episode a tragic mistake based on a misidentification of the vehicles, but have not explained more expansively how it happened. The cars were marked with World Central Kitchen logos, although the attack took place at night. Mr. Andrés has said his organization kept in touch with Israeli officials about movement plans.

As of Thursday morning, the Israelis had not yet communicated any initial findings of their promised investigation into the strikes to the United States, according to a senior Biden administration official who insisted on anonymity to detail internal conversations.

Mr. Biden’s shift on Thursday came as he absorbed withering criticism from Democrats. Among those speaking out have been former colleagues in the administration he served as vice president under President Barack Obama, who assailed him for voicing shock without taking action against Mr. Netanyahu, known by the nickname Bibi.

“The U.S. government is still supplying 2 thousand pound bombs and ammunition to support Israel’s policy,” Ben Rhodes, a former deputy national security adviser to Mr. Obama, wrote on social media on Wednesday. “Until there are substantive consequences, this outrage does nothing. Bibi obviously doesn’t care what the U.S. says, its about what the U.S. does.”

Jon Favreau, a former chief speechwriter for Mr. Obama, was even more derisive of Mr. Biden. “The president doesn’t get credit for being ‘privately enraged’ when he still refuses to use leverage to stop the IDF from killing and starving innocent people,” he wrote, referring to the Israel Defense Forces. “These stories only make him look weak.”

Some Palestinian advocates reacted with aggravation to Mr. Biden’s articulation of anger over the deaths of the aid workers because in their view he has not responded with nearly enough indignation over the killing of more than 32,000 people living in Gaza, most of them civilians.

The president evidently has taken heat even from within his own family. Mr. Biden told Muslim community leaders at the White House on Tuesday evening that the first lady, Jill Biden, had weighed in, telling him, “Stop it, stop it now, Joe.”

Julian E. Barnes, Katie Rogers and David E. Sanger contributed reporting from Washington, and Lara Jakes from Brussels.