Washington DC - US President Donald Trump said Wednesday that he may offer to reduce tariffs on China to get Beijing's approval for the sale of the popular social media platform TikTok.

"Maybe I give them a little reduction in tariffs or something to get it done," he told reporters at the White House.

Trump earlier this month said the US was in talks with four groups interested in acquiring TikTok, with the app facing an uncertain future in the country.

A US law has ordered TikTok to divest from its Chinese owner ByteDance or be banned in the US, enacted over concerns that Beijing could exploit the video-sharing platform to spy on Americans or covertly influence US public opinion.

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The law took effect on January 19, a day before Trump's inauguration, but he quickly announced a delay to the law which has allowed it to continue to operate.

That delay is set to expire on April 5.

"We're going to have a form of a deal," Trump said, adding that if it wasn't done in time, he would extend the deadline.

"China is going to have to play a role in that, possibly in the form of an approval and I think they'll do that."