President Donald Trump said on Saturday that the United States has knocked out much of Iran's military but still has to "take care of" one or two targets, as Tehran warned of reprisals if attacked.
Trump maintained that negotiations with Iran to end the war, which was started by the United States and Israel in February, were "going fine but you know they're not very reliable."
According to AFP, the Republican president said the United States is not in a hurry to take offensive action because it had already decimated Iran's military and nuclear program.
"We've knocked out their nuclear. We still have to take care of, I would say one or two sites, but we can do that in 10 minutes," Trump told reporters at his Florida residence.
"You probably could look at Pickaxe Mountain, and you have to take care of that. We can do that all very quickly," he added, referring to a suspected underground nuclear complex.
The Iranian government denied any nuclear work is carried out there.
Earlier Saturday, US Secretary of State Marco Rubio said Trump has not made a decision about fresh strikes on Iran and that the United States would be open to a diplomatic solution.
Iran's supreme leader on Saturday warned the United States and Israel against launching a new offensive, following threats they could resume strikes after crucial elections in both countries.
Trump had previously warned an attack could come after the US midterms this week, while Israeli Prime Minister Benjamin Netanyahu spoke of a "historic, one-time opportunity" to topple the Iranian government.
The elections in both countries could determine the direction of the conflict, with Israel having voted in a general election on Tuesday but yet to form a new government.
"Any level or type of threat must be met with an immediate, impactful and geographically unrestricted response," Iran's supreme leader Mojtaba Khamenei told top military commanders, according to a statement.
Khamenei also ordered commanders to update Iran's target list to include "all types of tangible and intangible assets belonging to the American-Zionist enemy".
This was the first reported meeting between Khamenei and military top brass.
The supreme leader has not been seen publicly since before he took the helm in March, after the killing of his father Ali Khamenei in US-Israeli strikes.
Rubio warned that "we can achieve military objectives if we seek to", adding that Trump had not made a decision on any fresh strikes.
Since the recent outbreak of the war, Tehran has restricted shipping through the Strait of Hormuz, which normally carries around one-fifth of global oil consumption.
Iran has previously warned it would also consider severing undersea cables in the Strait of Hormuz.
Fresh diplomatic efforts are underway to avert any resumption of fighting.
Qatari mediators landed in Tehran on Friday, and US Vice President JD Vance sent a letter to Iran's security chief Mohsen Rezaei.
"I read the letter," said Rezaei, head of Iran's supreme national security council, in a video broadcast on Iranian television.
"I haven't yet responded. Their tone has completely changed," he added, describing that as "a good sign" without going into more detail.
Iranian Foreign Minister Abbas Araghchi said there were currently no plans for meetings with US officials.
Rezaei insisted Iran would continue to blockade the Strait of Hormuz until its conditions, including releasing frozen assets, were met.
Qatar and Pakistan have been mediating between the warring parties, but the talks have yet to produce a lasting agreement.
Iranian army spokesman Mohammad Akraminia said any resumption of hostilities would only expand the scope of the war.
"The flames of war will undoubtedly engulf a much wider geographical area," he said on social media.
Araghchi warned on X that there would no longer be any "red lines".
