Washington DC - President Donald Trump said Sunday the US wants to help China, not hurt it, striking a conciliatory tone days after threatening an additional 100% tariff on the world's second-largest economy.

Trump's statements on Friday, as well as his threat to cancel a meeting with Xi later this month, sent Wall Street stocks tumbling into negative territory as traders worried the trade war between Washington and Beijing could reignite.

"The U.S.A. wants to help China, not hurt it!!!" Trump said in Sunday's post on Truth Social, adding that "respected President Xi [Jinping]... doesn't want Depression for his country."

Trump on Friday said that he would impose the extra levies from November 1 in response to what he called "extraordinarily aggressive" new Chinese export curbs on the rare-earths industry.

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Beijing, in turn, accused Washington of acting unfairly, with its Ministry of Commerce on Sunday calling Trump's tariff threat a "typical example of 'double standards.'"

The ministry said Washington had ratcheted up economic measures against Beijing since September.

"Threatening high tariffs at every turn is not the right approach to engaging with China," it said in an online statement.