Tokyo — The United States does not seek "regime change" in Iran despite mounting Middle East tensions, President Donald Trump said Monday, in dovish comments also praising North Korea's leader Kim Jong Un as a "very smart guy."

Speaking after summit talks with Japanese Prime Minister Shinzo Abe, Trump seemed at pains to dial down tensions in the world's two most pressing flashpoints as the US faces increasingly bellicose regimes in Tehran and Pyongyang.

Iran "has a chance to be a great country, with the same leadership. We're not looking for regime change, I want to make that clear. We're looking for no nuclear weapons," said the president.

"I really believe that Iran would like to make a deal. I think that's very smart of them and I think there's a possibility for that to happen also."

He had earlier opened the door to negotiations with Tehran, saying: "if they'd like to talk, we'd like to talk also."

Washington has decided to deploy 1,500 additional troops to the Middle East amid growing friction with Iran after Trump pulled out of a landmark nuclear deal and later re-instated tough sanctions.

Trump also appeared to give backing to his host Abe to mediate, amid reports the Japanese prime minister is considering a trip to Tehran to negotiate.

"I know for a fact that the prime minister (Abe) is very close with the leadership of Iran... nobody wants to see terrible things happen, especially me," Trump said before the summit.

"It has a chance to be a great country with the same leadership," Trump said. "We aren't looking for regime change -- I just want to make that clear. We are looking for no nuclear weapons."

Trump's comments came after his national security adviser John Bolton said on Saturday that the United States had "deep and serious" intelligence on threats posed by Iran.

During his joint news conference with Trump, Abe said Japan would do what it can on the Iran issue.

"Peace and stability of the Middle East is very important for Japan and the United States and the international community as a whole," Abe said. — Agencies