President Donald Trump said the US and Iran are nearing a "very good deal", but warned that if Washington's demands are not met, it would "end it in a different way."
Trump's remarks came during an interview to his daughter-in-law Lara Trump, which was telecast on Fox News on Saturday night.
"We're close to a very good deal. If you're going to be in a hurry, you're not going to make a good deal, and slowly but surely, we're getting what we want - and if we don't get what we want, we're going to end it a different way," Trump said.
Trump said the Iranians are "good negotiators," but argued that the United States now holds "all the cards" because Iran has been "militarily defeated."
"But we're close to a very good deal. If we can make it, good. Otherwise, we just start up with the Department of War, as we call it," the US President said.
Trump said the Iranians had stated they were not developing a nuclear weapon, but he countered by asking what if they bought one.
"I said, well what happens if you buy a nuclear weapon? So now it says we will not develop or in any way purchase a military weapon. That's a big difference," he said.
The American leader insisted that the US has "significant leverage" over Iran, as their navy and air force were "completely destroyed".
However, he said, the US has not fully dismantled Iran's military because some of the leadership was more moderate.
Trump said the US had targeted Iran's more extreme elements and key leadership.
The US President held a meeting with his top cabinet colleagues and officers of the armed forces in the situation room on Friday but it concluded without any clarity on future actions.
US media outlet Axios reported that Trump asked for several amendments to the deal his envoys reached with their Iranian counterparts.
Trump wants the deal and expects to finalize it soon, but is keen to strengthen several points that are important to him particularly around Iran's nuclear material, Axios reported quoting two US officials.
Trump's request has launched another round of back-and-forth between the parties that could last several days.
"It's more specifics about how the US gets the material and the timing," a senior administration official said, referring to the enriched uranium.
The second source told Axios that Trump also wants to amend some of the wording around the reopening of the Strait of Hormuz, which hosts roughly one-fifth of the world's energy supplies in normal times.
The US official said Trump was told it would take around three days before the Iranians get back with a response.
(With inputs from PTI)