US President Joe Biden has said reaching a six-week ceasefire deal in Gaza before the start of Ramadan is “looking tough”.
His comments come after the US secretary of state, Antony Blinken, said it was up to Hamas to make further progress on the truce.
“The ball is in their court,” he said.
“We’re working intensely on it, and we’ll see what they do,” Mr Blinken added ahead of a meeting with Turkish foreign minister Hakan Fidan on Friday.
He said the US remains “intensely focused” on securing a ceasefire.
Hamas left negotiations in Cairo on Thursday without a deal, dampening hopes an agreement will be reached before the start of the Muslim Holy month of Ramadan – which is expected to start on Sunday evening, depending on when a new moon is sighted.
The US had targeted a truce before Ramadan began.
Israel and Hamas have blamed each other for the lack of agreement.
Meanwhile, the Pentagon has denied that US aid airdrops caused civilian casualties in Gaza on Friday.
Palestinian officials reported that five people were killed and several others were wounded when boxes of aid fell on them by mistake.
Footage showed dozens of people running around as the boxes were dropped.
“Press reports that US airdrops resulted in civilian casualties on the ground are false,” a Pentagon spokesperson said.
“We have confirmed that all of our aid bundles landed safely on the ground.”