BEIJING (BLOOMBERG, REUTERS) - The latest tariff move by the United States has "seriously breached" the truce that Presidents Donald Trump and Xi Jinping agreed in Japan in late June and isn't doing any good to trade talks, according to a People's Daily commentary.

"It deviates from the correct track and is not conducive to solving the problem," the paper, mouthpiece of the Communist Party said on Saturday (Aug 3).

"The Chinese side is strongly dissatisfied and resolutely opposed."

Mr Trump announced on Thursday that he would impose a 10 per cent tariff on a further US$300 billion in Chinese imports, a move set to hit American consumers more directly than his other tariffs so far.

The new duties will be imposed beginning Sept 1 on a long list of goods expected to include smart-phones, laptop computers and children's clothing.

"The US's escalation of trade frictions and tariffs are inconsistent with the interests of the Chinese and American people and the interests of the world and will have a declining impact on the world economy," according to the commentary.

"China is committed to international cooperation, but is not afraid of any extreme pressure."

In a tweet, Mr Trump said China hadn't lived up to a promise Mr Xi made in Osaka to buy US agricultural goods and to halt illegal exports of fentanyl.

Chinese companies are making inquiries to buy more American farm products, the paper said.

The country is willing to strengthen its cooperation with the US on drug control, and is cracking down on illegal production and smuggling of fentanyl, it said.

The US needs to examine why it has an opioid crisis instead of blaming China, according to the commentary.

Meanwhile, China's new ambassador to the United Nations, Zhang Jun, said on Friday that if the US wanted to fight China on trade, "then we will fight" and warned that Beijing was prepared to take countermeasures over new US tariffs.

"China's position is very clear that if US wishes to talk, then we will talk, if they want to fight, then we will fight," he told reporters.

"We definitely will take whatever necessary countermeasures to protect our fundamental right, and we also urge the United States to come back to the right track in finding the right solution through the right way."