China has sent its strongest message yet to US President Donald Trump that it will not back down on its claims in the South China Sea.

In a rare move, a senior Chinese official used an English-language interview to warn the new administration not to challenge Beijing over the territorial disputes.

"There might be a difference [of opinion] over the sovereignty of these islands but it's not for the United States," Lu Kang, China's most senior Foreign Ministry spokesman, told NBC News.

"That might be between China and some other countries in this region."

For weeks Chinese officials and state-controlled media have warned the US to avoid any involvement in the territorial disputes in the strategic waterway, which involve another five claimants.

That has not appeared to work, with Mr Trump's press secretary Sean Spicer this week warning the US would seek "to defend international territories from being taken over by one country".

Mr Lu's English-language interview on a US network now appears to be aimed directly at Mr Trump — who has previously expressed his fondness for watching television news programs.

"[The South China Sea] is not the United States territory or the international territory as he mentioned," Mr Lu said.

Beijing also used the interview to reiterate China's unwillingness to bend on the "one China" principal, saying Beijing is "100 per cent" committed, and expects the same of Washington.

The one China principal is a condition China imposes upon other countries to accept if they want diplomatic relations with Beijing.

It forces governments to recognise the independently-ruled island Taiwan as part of one China, and to have no official relations with Taipei.

In November, then-President-elect Mr Trump rattled Beijing by accepting a phone call from Taiwan's President Tsai Ing-wen, and he has since further infuriated China by saying he will not commit to the decades-old one China position unless there is progress on trade issues.

China's US media outreach is an attempt to nip both the South China Sea issue and Taiwan in the bud, by making clear Beijing will not back down on territory it claims is "indisputable".

China also says US must tone down 'trade war' talk

But one other major issue of contention remains — trade.

China has been warning the US to tone down its "trade war" talk, stressing the threat of imposing new tariffs on Chinese goods would trigger counter measures.

While agricultural exports form the bulk of US exports to China, each year billions of dollars of Boeing planes and passenger vehicles are sold to China.

Analysts in Beijing appear to see trade as an area where China can help Mr Trump achieve his goal of boosting US jobs.

Already the e-commerce billionaire Jack Ma has met Mr Trump, and ambitiously pledged to create a million new jobs in the US through expanding his e-commerce network throughout the US.

Analysts and officials alike in China hope these sorts of initiatives will help create US jobs, help Chinese businesses and "make America great again" without hurting China's interests.