PALESTINIAN President Mahmoud Abbas says the US is the only country that can stop Israel from attacking Rafah, the southern Gaza city where more than a million people are taking refuge.
Mr Abbas, who runs parts of the occupied West Bank, said any attack could see Palestinians flee Gaza.
Israel has consistently vowed to carry out an offensive in Rafah.
US President Joe Biden “reiterated his clear position” on Rafah to Israel PM Benjamin Netanyahu in a call on Sunday.
The US has repeatedly said it cannot support a large-scale Israeli military operation in Rafah without seeing a credible plan to keep civilians out of harm’s way.
Speaking at the World Economic Forum (WEF) in the Saudi capital Riyadh earlier, Mr Abbas – whose Palestinian Authority is not present in Gaza, which has been under Hamas rule since 2007 – urged the US to intervene.
“We appeal to the United States of America to ask Israel to stop the Rafah operation because America is the only country capable of preventing Israel from committing this crime,” he said.
“What will happen in the coming few days is what Israel will do with attacking Rafah because all the Palestinians from Gaza are gathered there.”
He added that only a “small strike” on Rafah would force the Palestinian population to flee the Gaza strip.
“The biggest catastrophe in the Palestinian people’s history would then happen.”
Israeli Prime Minister Benjamin Netanyahu has consistently vowed to carry out an offensive in Rafah as a next step in military actions against Hamas.
But on Saturday, Israel’s foreign minister said Israel could suspend the incursion if there was a hostage deal.
“The release of the hostages is the top priority for us,” Israel Katz said.
Long-running talks mediated by Egypt and Qatar have largely stalled because of the gaps between the Israeli and Hamas positions, but on Sunday Hamas said it would send representatives to Cairo to give a response to the latest proposal.
Hamas wants a permanent end to the war and withdrawal of all Israeli troops from Gaza, while Israel insists Hamas must be destroyed in Gaza and all hostages freed.
Egypt and other Arab states have previously said an influx of Palestinian refugees fleeing the war would be unacceptable because it would amount to the expulsion of Palestinians from their land.
US secretary of state Antony Blinken is due to arrive in Riyadh later on Sunday and hold talks with Mr Abbas.