Trump unafraid of China trade war: Mnuchin

US Treasury Secretary Steve Mnuchin has told Fox News President Donald Trump is not afraid of a trade war with China although that is not his intention.

Treasury Secretary Steve Mnuchin insists President Donald Trump isn't afraid of a Chinese trade war. (AAP)

US Treasury Secretary Steve Mnuchin says President Donald Trump has no intention of backing down and isn't worried about a trade war despite threats of retaliation from China over US plans to impose tariffs on up to $US60 billion in Chinese goods.

"We are going to proceed with our tariffs. We're working on that," Mnuchin told Fox News Sunday. "So, as President Trump said, we're not afraid of a trade war, but that's not our objective."

Fears of a trade war between the US and China have sent US stock prices tumbling. The Dow Jones Industrial Average and the S&P 500 both lost nearly 6 per cent by the end of last week.

A presidential memorandum signed by Trump last week will target up to $US60 billion in Chinese goods with tariffs over what his administration says is misappropriation of US intellectual property, but only after a 30-day consultation period that starts once a list is published.

Trump gave the Treasury Department 60 days to develop investment restrictions aimed at preventing Chinese-controlled companies and funds from acquiring US firms with sensitive technologies.

Mnuchin said he believed the US could reach an agreement with China on some issues, but said the tariffs would not be put on hold "unless we have an acceptable agreement that the president signs off on".

China has urged the US to "pull back from the brink" on the tariffs and threatened to retaliate by hitting US agricultural exports.

Without giving a time frame, China's commerce ministry said the government was considering a 25 per cent tariff on US pork. It did not announce potential tariffs on soy.

Republican senator Joni Ernst of Iowa, a major exporter of farm products to China, said on the CBS program Face the Nation on Sunday that hers and other Midwestern states would be harmed by any retaliation.

Iowa is the top US state for hog production. China imports more than a third of all US soybeans.

"Nobody wins in a trade war," she said. "So if they start retaliating, we will see significant impact - very detrimental impact not just in Iowa, but across the Midwest as well," she said.