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The US said on Friday that it had proposed a "bridge" plan to extend the ceasefire in Gaza, but accused Hamas of publicly claiming flexibility while privately making "entirely impractical" demands.
A statement released by the office of US special Middle East envoy Steve Witkoff said the proposal presented on Wednesday was meant to extend the truce through the middle of April, after the end of Ramadan and the Jewish holiday of Passover, to allow time to negotiate a permanent ceasefire.
It also called for the immediate release of dual US-Israeli citizen Edan Alexander, who is being held by Hamas.
Mr Witkoff was in Doha this week and met mediators from Qatar, Egypt and Israel to discuss ceasefire efforts, which the White House accused the Palestinian militant group of derailing.
"Hamas is making a very bad bet that time is on its side. It is not," Mr Witkoff was quoted by his office as saying. "Hamas is well aware of the deadline, and should know that we will respond accordingly if that deadline passes."
The development comes nearly two weeks after a the first phase of the ceasefire deal in Gaza ended without an agreement on how to proceed.
Israel has stopped the flow of all food and electricity into war-torn Gaza, home to about two million Palestinians, to pressure Hamas into making concessions. The move has drawn accusations of collective punishment by the UN and other aid groups.
The war began on October 7, after Hamas launched an attack on Israel, killing about 1,200 people, with about 250 taken hostage. Israel responded by launching a punishing military campaign on Gaza that has killed more than 47,000 people. It has also levelled much of the territory.
Israel believes about 25 hostages are still alive and being held by Hamas and other groups. In the statement, the White House warned that Hamas should either release hostages immediately or be prepared to "pay a severe price".
President Donald Trump, who took office on the day after the ceasefire came into effect, has said that securing the release of hostages is a priority.
He has also floated a proposal to permanently resettle Palestinians from Gaza abroad, to make way for a plan to turn the coastal enclave into the the "Riviera of the Middle East". He appeared to walk this back somewhat this week, however, telling reporters that "nobody is expelling any Palestinians” from Gaza.