China firmly opposes the United States' new threat to impose additional tariffs on about $550 billion worth of Chinese imports, a spokesperson of the Ministry of Commerce said on Saturday.

In a brief statement, the ministry said the US act is unilateral, trade protectionism, and using maximum pressure.

It violates the consensus reached between the top leaders of the two countries, severely undermines the multilateral trading system and normal international trade order, and Washington will eat the bitter fruits of its own action, the ministry said.

"Such unilateral and bullying acts of trade protectionism and extreme pressure run counter to the consensus of the heads of state of China and the United States, and run counter to the principles of mutual respect, equality and mutual benefit," the spokesperson said.

The ministry urged Washington to immediately stop its wrongful deeds, otherwise it will "bear all the consequences."

The ministry warned the US administration not to misjudge the situation, nor to underestimate the determination of the Chinese people.

"China strongly urges the United States not to misjudge the situation, or underestimate the determination of the Chinese people. It must immediately stop its erroneous practices, or bear all the consequences," the spokesperson said.