Secretary of State Antony Blinken raised US opposition to a major ground operation in Rafah with Israel's defence minister on Monday, after a delegation to discuss Washington's concerns was scrapped earlier in the day.
Prime Minister Benjamin Netanyahu had agreed to send the delegation to Washington but cancelled it after the United States abstained on a UN Security Council resolution that demanded an immediate ceasefire during Ramadan.
In his meeting with Israeli Defence Minister Yoav Gallant in Washington, Blinken reiterated US "opposition to a major ground operation in Rafah," State Department spokesman Matthew Miller said in a statement.
Such a move "would further jeopardise the welfare of the more than 1.4 million Palestinian civilians sheltering there," Miller said.
Netanyahu's determination to launch a ground operation in Rafah, the city on Gaza's southern border where most of the territory's population is sheltering, has become a key point of contention.
Blinken "underscored that alternatives exist to a major ground invasion that would both better ensure Israel's security and protect Palestinian civilians," Miller said.
The two additionally "discussed the need to immediately surge and sustain additional humanitarian assistance to meet the needs of civilians in Gaza," he added.
Israel claims to be targeting Hamas in its onslaught, but its military operation has killed over 32,000 Palestinians - mostly women and children, and has destroyed most of the territory's infrastructure, leaving scores displaced and homeless.
Israel said earlier in the day that the United States abstention "hurts" both its war effort and attempts to release hostages.
It was "a clear retreat from the consistent position of the US," Netanyahu's office said.