US President Donald Trump, after shocking markets with the risk of a global trade war, has come under intense pressure from US business interests and foreign trading partners to moderate his threat to impose tariffs on steel and aluminum imports.

Mr Trump dispatched pro-tariff advisers Wilbur Ross and Peter Navarro to TV news studios to defend his plan, while White House aides scrambled to downplay the prospect of a resignation by free trade advocate Gary Cohn, the top White House economic adviser, over the matter.

Mr Cohn is part of a faction in Mr Trump's administration that warned the Republican president for months not to threaten the 25% steel and 10% aluminum tariffs that he pledged to impose in a chaotic announcement on Thursday.

There was speculation that Mr Cohn, who told Mr Trump the markets would slump on a tariffs threat, might step down as a result of Mr Trump's decision, but there was no indication of a such a move anytime soon, a senior White House official said.

"Gary was here yesterday afternoon, I talked to him in my office several times, so I don't have any reason to think otherwise," White House spokeswoman Sarah Sanders told reporters.

Turmoil inside the administration over trade came during one of the most hectic weeks of the Trump presidency, with confusion around the issue intensified by adviser Hope Hicks' resignation on Wednesday and staff secretary Rob Porter's on 7 February.

National Economic Council Director Cohn, Treasury Secretary Steven Mnuchin and others for months had tried to steer Mr Trump away from aggressive tariffs, but the president resisted their counsel, a senior administration official said.

Interviews with large trade associations, as well as lobbyists who represent companies in several industries, indicated back-channel discussions were under way, with companies trying to convince the White House and Commerce Department to include key exemptions in the coming official tariffs policy.

Industry groups want exemptions for imports from individual countries or for types of metals that cannot be found in the United States, the lobbyists said.

Companies that use cans for products like drinks or soup were among the most vocal opponents.

"Like most brewers, we are selling an increasing amount of our beers in aluminum cans and this action will cause aluminum prices to rise and is likely to lead to job losses across the beer industry," said Miller Coors spokesman Colin Wheeler.

Mr Trump's attitude on tariffs should not come as a surprise, Commerce Secretary Ross said in a CNBC interview.

"The president has been consistent all the way from his campaign days to the present about doing something big to protect steel and aluminum, so it should not have come as a shock," Mr Ross said.

Mr Trump said on Thursday his tariffs plan would safeguard American jobs in the face of cheaper foreign products and would be formally announced next week.

"When a country (USA) is losing many billions of dollars on trade with virtually every country it does business with, trade wars are good, and easy to win," he wrote on Twitter yesterday.

Turkey's Deputy Prime Minister Mehmet Simsek, responding to the tweet," wrote on Twitter, "There are no winners in global trade wars."

Stock indexes recouped some losses yesterday, but ended the week in the red as investors fretted over a possible global trade war.