U.S. President Donald Trump on Friday said Iran has his administration's proposal and knows it needs to move quickly, a day after saying Washington and Tehran were close to a nuclear deal.

"They have a proposal. More importantly, they know they have to move quickly or something bad—something bad's going to happen," Trump told reporters aboard Air Force One after departing the United Arab Emirates, according to an audio recording of the remarks.

An Iranian source close to the negotiating team, said Tehran has yet to receive the U.S. proposal, "but Oman has got it and will hand it over to Tehran soon".