US President Donald Trump said he was confident that China was sincere about wanting a trade deal with the United States because it had taken "a very large hit" in recent months.

"I think they want to make a deal very badly. I think that was elevated last night. The vice chairman of China came out, he said he wants to see a deal made," Trump told a news conference at the end of G7 summit in Biarritz, France.

"He wants it to be made under calm conditions ... I agree that China has taken a very large hit in the last few months. Three million jobs. It will soon be much more than 3 million jobs. Their chain is breaking up like no one has seen before. Once that happens it is very hard to put it back together. I think they very much want to make a deal."

Earlier on Monday, Trump sounded a more conciliatory note, saying he believed China wanted to make a trade deal after it contacted US trade officials overnight to say it wanted to return to the negotiating table.

The statement comes after US President Donald Trump on Friday announced an extra 5% duty on some $550 billion of Chinese goods, following China's announcement of retaliatory tariffs on $75 billion of imports from the United States.

Speaking on the sidelines of a G7 summit in Biarritz, Trump hailed Chinese President Xi Jinping as a great leader and said the prospect of talks was a very positive development for the world.

"China called last night our top trade people and said, 'let's get back to the table', so we'll be getting back to the table, and I think they want to do something," he said.