US President Joe Biden said Monday he had told Israeli Prime Minister Benjamin Netanyahu to send a team to Washington to discuss how to avoid an all-out assault in the southern Gaza city of Rafah.

The move is one of the clearest attempts yet by Biden to rein in the key US ally, amid fears that the already huge death toll and humanitarian crisis in Gaza could be drastically worsened by a full attack on Rafah.

The White House said separately that Israel had killed one of Hamas's top commanders in a strike in Gaza.

"I asked the Prime Minister to send a team to Washington to discuss ways to target Hamas without a major ground operation in Rafah," Biden said on X after speaking to Netanyahu for the first time in more than a month.

Biden also "reiterated the need for an immediate ceasefire as part of a deal to free hostages, lasting several weeks, so we can get hostages home and surge aid to civilians in Gaza."

Roughly 1.5 million people are sheltering in Rafah, most of them displaced by Israel's relentless assault on other parts of Gaza since the October 7 Hamas attacks on Israel.

The White House earlier said Biden had warned Netanyahu that an offensive on Rafah would be a "mistake", in their first call since February 15.

"A major ground operation there would be a mistake," National Security Advisor Jake Sullivan told reporters.

"It would lead to more innocent civilian deaths, worsen the already dire humanitarian crisis, deepen the anarchy in Gaza, and further isolate Israel internationally."

Netanyahu agreed to send a team of senior Israeli officials to Washington in coming days to discuss "alternative approaches that would target key elements of Hamas", he added.

Sullivan separately confirmed that Israel had killed Hamas's third-in-command, Marwan Issa, in an operation last week. Israel previously said he had been targeted in a Gaza airstrike but did not confirm his death.

- 'Threat to Israel' -

Biden has supported Israel since the October 7 attacks, sending billions of dollars in military aid, but has become increasingly frustrated by Netanyahu's failure to curb civilian deaths or let in vital aid.

The US president also faces growing political pressure at home, with opposition among Arab-Americans and young voters posing a risk to his reelection chances in November.

Netanyahu said in a statement after the Biden call that he had reiterated "Israel's commitment to achieving all of the war's objectives."

He cited the objectives as eliminating Hamas, winning the release of all hostages held by the group and "ensuring that Gaza will never present a threat to Israel."

He also pointed to the provision of "essential humanitarian aid that helps achieve these aims."

Biden was caught on a hot mic just over a week ago saying he would have a "come-to-Jesus meeting" with Netanyahu.

He also praised a "good speech" last week by Democratic Senate Majority Leader Chuck Schumer calling for new elections in Israel.

With the UN warning of imminent famine in Gaza, Biden earlier this month ordered the US military to start airdrops of food into the enclave and has sent a temporary US port there to speed up delivery of maritime aid.

Israel began relentless bombardment in Gaza, alongside a ground offensive, after Hamas's unprecedented October 7 attack, which left about 1,160 dead in Israel, mostly civilians, according to an AFP tally of official figures.

The militants also seized hostages, around 130 of whom Israel believes remain in Gaza, including 33 presumed dead.

Nearly 32,000 people have been killed in Gaza since the war began, most of them women and children, according to the health ministry in the Hamas-run territory.