Trump told reporters before leaving for Beijing that "we're going to have a long talk about it."

China is a top economic partner of Iran, buying much of its oil output, and also an important diplomatic backer.

However, Trump underlined that he does not need Xi to find an exit from the conflict that started two and a half months ago with a massive US-Israeli attack before settling into a stalemate over control of the Strait of Hormuz shipping route.

"We have a lot of things to discuss. I wouldn't say Iran is one of them, to be honest with you, because we have Iran very much under control," Trump said.

"We're either going to make a deal or they are going to be decimated."

Amid reports that China continues to help arm Iran and purchase sanctioned oil, Trump said Xi has "been relatively good."

"They get a lot of their oil from that area. We've had no problem. And he's been a friend of mine. He's been somebody that we get along with."