Asked if he was considering a limited strike to pressure Iran into a deal on its nuclear program, Trump told reporters at the White House on Friday: "I guess I can say I am considering" it.
Asked later about Iran at a White House press conference, he said, "They better negotiate a fair deal."
Two US officials told Reuters that US military planning on Iran has reached an advanced stage, with options including targeting individuals as part of an attack and even pursuing leadership change in Tehran, if ordered by Trump.
Iranian Foreign Minister Abbas Araqchi, in an interview earlier on Friday on MS NOW, said his draft counterproposal could be ready in the next two or three days for top Iranian officials to review, with more US-Iran talks possible in a week or so.
Military action would complicate efforts to reach a deal, he added.
Araqchi said after indirect discussions in Geneva on Tuesday with US Special Envoy Steve Witkoff and Trump's son-in-law Jared Kushner that the sides reached an understanding on main "guiding principles," but that did not mean a deal was imminent.
On Thursday, Trump gave Tehran a deadline of 10 to 15 days to make a deal or face "really bad things" amid a US military buildup in the Middle East that has fuelled fears of a wider war.
Araqchi gave no specific timing as to when Iranians would get their counterproposal to Witkoff and Kushner, but said he believed a diplomatic deal was within reach and could be achieved "in a very short period of time".
At the United Nations, spokesman Stephane Dujarric reiterated concerns about heightened rhetoric and increased military activities in the region.
"We encourage both the United States and the Islamic Republic of Iran to continue to engage in diplomacy in order to settle the differences," he told a regular news briefing.
During the Geneva talks, the US did not seek zero uranium enrichment and Iran did not offer to suspend enrichment, Araqchi told MS NOW, a US cable television news network.
"We have not offered any suspension and the US side has not asked for zero enrichment," he said.
"What we are now talking about is how to make sure that Iran's nuclear program, including enrichment, is peaceful and would remain peaceful forever."
He added that technical and political "confidence-building measures" would be enacted to ensure the program would remain peaceful in exchange for action on sanctions, but he gave no further details.
"The president has been clear that Iran cannot have nuclear weapons or the capacity to build them, and that they cannot enrich uranium," the White House said when asked about Araqchi's comments.
