MORRISTOWN, NEW JERSEY (REUTERS) - United States President Donald Trump said on Thursday (Aug 15) that he believes China wants to make a trade deal and the trade war with Beijing will be fairly short.

"I think we're having very good discussions with China. They very much want to make a deal," Mr Trump told reporters.

He said he had a call scheduled soon with Chinese President Xi Jinping, but he did not say when.

"I think the longer it goes the stronger we get," Mr Trump said of the trade war. "I have a feeling it's going to go fairly short."

China on Thursday vowed to counter the latest US tariffs on US$300 billion (S$416 billion) of Chinese goods but called on the US to meet it halfway on a potential trade deal.

Mr Trump said he did not think Beijing would retaliate for the US tariffs.

US and Chinese trade negotiators are set to meet next month in Washington, though a specific date has not been announced.

"September, the meeting is still on as I understand it, but I think more importantly than September, we're talking by phone, and we're having very productive talks," Mr Trump said.

He said US and Chinese officials had "a very good conversation" a few days ago.

Earlier on Thursday, Mr Trump said any trade deal the US makes with China must be on US terms.

"China, frankly, would love to make a deal, and it's got to be a deal on proper terms. It's got to be a deal, frankly, on our terms. Otherwise, what's the purpose?" Mr Trump said in an interview on New Hampshire radio station WGIR.

He also urged Mr Xi to personally meet the protesters in Hong Kong, saying it would lead to an end to tensions that have seized the territory for weeks.

"If President Xi would meet directly and personally with the protesters, there would be a happy and enlightened ending to the Hong Kong problem. I have no doubt!" Mr Trump tweeted.

His tweet came a day after he tied a US trade deal with China to a humane resolution of the weeks of protests wracking Hong Kong. He made that comment hours after the State Department said it was "deeply concerned" about reports of movement of Chinese paramilitary forces along the Hong Kong border.

Mr Trump, who has been seeking a major deal to correct trade imbalances with China ahead of his 2020 re-election bid, has faced criticism from Congress and elsewhere for not taking a stronger public line on Hong Kong and for his characterisation of the protests earlier this month as "riots" that were a matter for China to deal with.

His tougher stance on Hong Kong followed a debate within his administration over whether Washington was looking too compliant while China appeared to be preparing for a crackdown, a source familiar with the deliberations said.

A White House aide said television reports on the possibility of a crackdown were a factor in Mr Trump's shift in tone.

On Thursday, China's foreign ministry said Beijing had noted Mr Trump's comment that Beijing needed to resolve the Hong Kong crisis on its own, while Mr Liu Xiaoming, the Chinese ambassador in London, accused unidentified foreign forces of fomenting the protests.

"Hong Kong is part of China. No foreign country should interfere in Hong Kong's internal affairs," Mr Liu said.