US President Joe Biden has no plans to change his Israel policy following a deadly weekend strike on Gaza's Rafah -- but is not turning a "blind eye" to the plight of Palestinian civilians, the White House said Tuesday.

Gazan health authorities said 45 people were killed as a blaze tore through a camp for displaced people following the Sunday strike by Israel.

But Washington does not believe that Israel's actions in Rafah amount to a full-scale operation that would breach Biden's "red lines," National Security Council spokesman John Kirby said.

"As a result of this strike on Sunday I have no policy changes to speak to," Kirby told a White House briefing. "It just happened, the Israelis are going to investigate it."

Kirby added however that "this is not something that we've turned a blind eye to" when asked "how many charred corpses" it would take for Biden to change course on the issue.

Biden has previously said he would not support a major Israeli military offensive in Rafah, from which one million civilians have fled, and earlier this month paused a shipment of heavy bombs to Israel over concerns they could be used against the southern Gazan city.

Witnesses told AFP that Israeli tanks were stationed in the center of Rafah on Tuesday, after intense fighting between Israeli forces and Palestinian militants in recent weeks.

But under repeated questioning Kirby insisted that the president was not "moving the stick" on how to define a major military offensive against Rafah.

"We have not seen them smash into Rafah," he added.

"We have not seen them go in with large units, large numbers of troops, in columns and formations in some sort of coordinated maneuver against multiple targets on the ground."

- No to ICC sanctions -

The Pentagon had earlier said that it considers Israel's assault on Rafah as "limited in scope."

Deputy Pentagon Press Secretary Sabrina Singh also said the administration was waiting for the Israeli military to conclude its investigation into Sunday's strike before commenting further.

"We certainly take seriously what happened over the weekend. We've all seen the images. They're absolutely horrific," Singh added.

Earlier US State Department spokesman Matthew Miller said Israel's preliminary investigation suggested that the strike was carried out using "the smallest bomb in their arsenal."

Israel has called the loss of life "a tragic accident" and its army said Tuesday its munitions alone could not have caused the deadly blaze, adding that it had targeted and killed two senior Hamas militants in the strike.

The White House also said it did not support calls from Republicans in Congress for sanctions against the International Criminal Court after its prosecutor sought an arrest warrant for Israeli Prime Minister Benjamin Netanyahu.

"We don't believe that sanctions against the ICC is the right approach here," Kirby said, although he added that the United States still did not believe the war crimes court had jurisdiction.

Separately, the Pentagon said the US military has suspended aid deliveries into the Gaza Strip by sea after its temporary pier was damaged by bad weather.