President Donald Trump on Sunday said the US and Iranian officials can talk by phone for a peace solution to the conflict.

In an interview on Fox News Channel, Trump said he made that decision rather than send a delegation on a 17-hour flight.

"We have all the cards. If they want to talk, they can come to us, or they can call us," Trump said, not indicating when the call would take place.

Talks appeared to fall apart on Saturday, with Tehran's top diplomat leaving Pakistan, and Trump soon afterward saying he had told envoys not to travel to Islamabad.

Asked about NATO, Trump said he was "very, very disappointed" in the military alliance, which he has suggested the US may consider leaving after member countries ignored his call to help as Iran effectively shut the the Strait of Hormuz.

"We've been serving them for many years, spending trillions of dollars, and when we wanted to help they were not there, so we have to remember that," Trump said.