President Donald Trump says the US will "leave" Iran in "two to three weeks" when it is certain the regime cannot build a nuclear weapon "for years" and whether there is a deal with Tehran or not.

Speaking from the Oval Office, Trump said Iran is "begging to make a deal" but whether it happens or not is "irrelevant" to America's timetable.

Earlier, Iranian President Masoud Pezeshkian said Tehran had the "necessary will" to end the war provided its enemies guaranteed it would not flare up again.

Meanwhile, Trump is set to give an "important update on Iran" in a national address scheduled for Wednesday night.

The remarks underscored the shifting and at times contradictory timelines and statements from Washington about how and ‌when the war, now in its fifth week, might end, said a Reuters report.

"We'll be leaving very soon," Trump told reporters at the White House on Tuesday, saying the exit could take place "within two weeks, maybe two weeks, maybe three."

Asked if successful diplomacy was a prerequisite for the US to end what it calls "Operation Epic Fury", Trump said it was not.

"Iran doesn't have to make a deal, no," he said. "No, they don't have to make a deal with me."

Washington had previously threatened to intensify operations if Tehran did not accept a 15-point U.S. ceasefire framework that had among its core demands that Iran commit ​not to pursue nuclear weapons, halt all uranium enrichment and fully reopen the Strait of Hormuz.