Beijing, China - China on Thursday warned the US and other regional countries against signing trade deals designed to "hurt third parties" after President Donald Trump signed a deal with Vietnam.

"China has always advocated that all parties resolve economic and trade differences through equal dialogue and consultation," said Chinese foreign ministry spokesperson Mao Ning during a daily press conference on Thursday.

"At the same time, relevant negotiations and agreements should not target or harm the interests of third parties."

Mao's comments come after the US struck a trade deal with Hanoi on Wednesday, reducing the tariff on exports from Vietnam to 20% in exchange for opening its market to US products, including cars.

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A 40% tariff will hit goods passing through the country to circumvent steeper trade barriers. This is largely in response to accusations made by Washington that Hanoi is relabelling Chinese goods to avoid tariffs.

The Trump administration is on a mission to forge deals that are designed to isolate Chinese companies and firms from global trade supply chains.

A similar deal is in the works with India, where Washington wants at least 60% of a product to be produced within the country before it can be legally classified as "Made in India."

China has opposed such deals, on Saturday saying that it "firmly opposes any party reaching a deal at the expense of Chinese interests in exchange for so-called tariff reductions."

"If this happens, China will never accept it and will resolutely counter it to safeguard its legitimate rights and interests."

Trump called the deal with Vietnam a "Great Deal of Cooperation between our two Countries" in a Wednesday statement on Truth Social.

"Vietnam will do something that they have never done before, give the United States of America TOTAL ACCESS to their Markets for Trade."