The cease-fire between the United States and Iran remained in limbo after President Trump said Saturday evening on social media that he was reviewing Iran’s latest proposal but “can’t imagine that it would be acceptable.”

The comments came one day after Mr. Trump had flatly said he was “not satisfied” with the latest offer from Iran, which Iranian state media said was sent to Pakistani mediators on Thursday evening. But on Saturday evening, the president clarified to reporters that he had only been briefed on the “concept of the deal” and had not seen the details.

“They’re going to give me the exact wording now,” he said, just before boarding an airplane in Palm Beach, Florida.

In the post on Truth Social, Mr. Trump cast doubt that the latest proposal would satisfy him, asserting that Iran has “not yet paid a big enough price for what they have done to Humanity, and the World, over the last 47 years.”

In a meeting with foreign diplomats in Tehran on Friday, the country’s deputy foreign minister, Kazem Gharibabadi, placed the onus on the United States to end the war.

“The ball is now in the United States’ court to choose between diplomacy or continuing a confrontational approach,” he said, according to Iranian state media. He added that Iran was prepared to fight if military conflict between Iran and the United States resumed.

On Friday, Mr. Trump said he was weighing all of his options, which included breaking the cease-fire. “Do we want to go and just blast the hell out of them and finish them forever, or do we want to try and make a deal?” he told reporters at the White House. “I mean, those are the options.”

Iran’s new proposal no longer requires Mr. Trump to lift the blockade on Iranian shipping in the Strait of Hormuz before negotiators meet face to face, according to two senior Iranian officials. They said Iran was also willing to open the strait, a vital oil route, before Mr. Trump announced an end to the blockade.

While Iran would reopen the strait under the proposal, unblocking a waterway through which a fifth of the world’s oil traveled before the war, Iranian officials said they would not discuss the future of the country’s nuclear program until a later phase of talks after a permanent cease-fire was reached.

At an event Friday evening in Florida, Mr. Trump said: “They’re not coming through with the kind of deal that we have to have, and we’re going to get this thing done properly. We’re not going to leave early and then have the problem arise in three more years.”

Mr. Trump has repeatedly insisted that Iran cannot have nuclear weapons and should halt all of its nuclear enrichment, a major sticking point in negotiations that appears difficult, if not impossible, to reconcile with Iran. Iran has maintained it has a right to nuclear enrichment.

Mr. Trump had extended a cease-fire with Iran on April 21, even as talks stalled between U.S. and Iranian negotiators. Days later, he suddenly called off a trip by two of his top negotiators to Pakistan, saying that Iran can call him with a better offer.

Yeganeh Torbati and Leily Nikounazar contributed reporting.