Israel will pause military action in northern Gaza each day for civilians to flee, the White House said.

Israel has agreed to put in place daily four-hour pauses in the fighting with Hamas in selected areas of northern Gaza to allow civilians to flee, the White House announced on Thursday, culminating days of pressure from President Biden as the casualty toll mounts.

For several days, Israel has allowed people to evacuate northern Gaza for a four-hour period each day along a single corridor, passing through Israeli military lines as they head south. The White House said a second corridor for evacuations would be opened along a coastal road and that the daily pauses would be institutionalized to include advance notice of at least three hours.

“We have been told by the Israelis that there will be no military operations in these areas over the duration of the pause and that this process is starting today,” John F. Kirby, a White House spokesman, told reporters on a conference call. “These are good steps in the right direction,” he added, saying the White House hoped the pauses would continue “for as long as they’re needed.”

Mr. Kirby said the daily pauses would not only provide a greater opportunity for civilians to escape the fighting but also permit the delivery of more humanitarian supplies and possibly facilitate the release of some of the more than 200 hostages held by Hamas, including a handful of Americans. He noted that 106 trucks of humanitarian aid crossed into Gaza on Wednesday.

“We need to see more and need to see more soon,” he said.

In Israel, Prime Minister Benjamin Netanyahu’s office said in a statement that his country’s forces were permitting safe passage to the south of Gaza, adding that 50,000 Gazans had taken that route on Wednesday alone. But the statement added: “The fighting is continuing and there will be no cease-fire until our hostages are released. We again call on the civilian population in Gaza to evacuate to the south.”

The announcement of daily pauses in two corridors came after days of efforts by Mr. Biden and his team to persuade Israel to do more to minimize civilian casualties. Mr. Biden asked Mr. Netanyahu during a call on Monday to pause its assault on Hamas. Secretary of State Antony J. Blinken pressed the case during a visit to the region, and other officials, including Defense Secretary Lloyd J. Austin III and Jake Sullivan, the president’s national security advisers, lobbied their counterparts.

“I’ve asked for a pause longer than three days,” Mr. Biden told reporters on Thursday before a trip to Illinois. Asked if he was frustrated that Mr. Netanyahu took so long to agree, the president hinted at some impatience. “It’s taken a little longer than I hoped,” he said. As for the fate of the hostages, he said, “We’re still optimistic.”

But Mr. Biden has not joined the calls by some in his party and around the world for a full cease-fire, reasoning that Israel has a legitimate interest in destroying Hamas after its Oct. 7 terrorist attack killed more than 1,400 people. He ruled out the prospect of a cease-fire again on Thursday, saying: “None. No possibility.”

Mr. Kirby said a cease-fire would not be wise. “We still don’t believe a cease-fire is appropriate at this time,” he said, adding that “Hamas benefits from it.”

“Frankly, a cease-fire at this time would in all practicality legitimize what they did on Oct. 7, and we simply aren’t going to stand for that at this time,” Mr. Kirby said.

He made a point of expressing sympathy for Israel’s military challenge in taking on Hamas while avoiding civilian casualties.

“It’s fighting an enemy that is embedded in the civilian population, using hospitals and civilian infrastructure in an effort to shield itself from accountability and to place the innocent Palestinian people at greater risk,” Mr. Kirby said. “At the same time, Israel has an obligation to fully comply with international law. And we believe these pauses are a step in the right direction, particularly to help ensure that civilians have an opportunity to reach safer areas away from the act of fighting.”