President Donald Trump told a news network on Sunday the United States could become involved in the Iran-Israel conflict, and that he would be "open" to his Russian counterpart Vladimir Putin being a mediator.

The Republican president, according to ABC News, also said talks over Iran's nuclear programme were continuing and that Tehran would "like to make a deal," perhaps more quickly now that the Islamic republic is trading massive strikes with Israel.

"It's possible we could get involved" in the ongoing battle between the Middle East arch-foes, Trump said in an off-camera interview with ABC News senior political correspondent Rachel Scott that was not previously publicised.

He stressed that the United States is "not at this moment" involved in the military action.

'Long talk' with Putin about Israel-Iran conflict

As for Putin being a potential mediator in the conflict, "he is ready. He called me about it. We had a long talk about it," Trump said.

Israel and Iran traded heavy aerial assaults for a third straight day on Sunday, with casualties mounting following Israel's large-scale attacks aimed at crippling Iran's nuclear and military infrastructure, sparking retaliation.

Oman, which has acted as a mediator on the nuclear issue, has said a sixth round of talks between Iran and the United States planned for this weekend had been cancelled.

But Trump said the two sides were continuing discussions.

'No deadline' on negotiations

"No, there's no deadline" on negotiations, he told ABC when asked whether there was a time limit for Tehran to come to the table.

"But they are talking. They'd like to make a deal. They're talking. They continue to talk," Trump said, according to Scott.

Trump suggested that something like the clash between Israel and Iran "had" to happen to spur talks on a nuclear agreement.

It "may have forced a deal to go quicker, actually," Trump said.