As the Group of Seven ministerial opened in Canada, US Treasury Secretary Steven Mnuchin faced stern reaction from his counterparts, who accused Trump of jeopardising the world economy with steps that would prove job killers for all concerned.
Britain has stressed the importance of United Kingdom steel to the American defense industry.
The new 25 percent tariff on steel imports and 10 percent tariff on aluminum imports from the EU, Canada and Mexico come into force at midnight (04:00 GMT, Friday), according to US Commerce Secretary Ross.
The tariffs his administration has imposed - 25 percent on imported steel, 10 percent on aluminum from Canada, Mexico and the European Union - threaten to drive up prices for American consumers and companies and heighten uncertainty for businesses and investors around the globe.
Canada responded with duties of 25% on USA steel and aluminium, and 10% on consumer goods such as ketchup, orange juice, sailboats and washing machines, which will take effect July 1.
Ross, who was preceded in Beijing this week by more than 50 US officials, is expected during the two-day visit to try and secure long-term purchases of USA farm and energy commodities to help shrink the US trade deficit.
UK's Prime Minister, Theresa May has slammed Donald Trump, for his decision to impose tariffs on steel and aluminium producers, a decision that is pushing European Union to the brink of a trade war with the US.
"We follow this with a lot of anxiety", Malmström said of the investigation.
In a statement the EU said European companies coming to China were forced to grant ownership or usage rights of their technology to domestic Chinese entities and did not have the ability to freely negotiate market-based terms in technology transfer agreements.
"We are determined to protect the multilateral system", EU Trade Commissioner Cecilia Malmstrom said.
However, the Canadian industry has been less damaged than had been anticipated as duties imposed by the USA government have been passed on to US consumers in the form of higher prices.
"This is stupid - it's counterproductive", Francis Maude, a former British trade minister, told the BBC.
Dr Merkel said the measure "risks touching off spirals of escalation that in the end hurt everyone". But companies in the USA that use imported steel will face higher costs.
Meanwhile, in Washington, Trump floated the possibility of scrapping the 24-year-old North American Free Trade Agreement in favour of separate bilateral deals with Canada and Mexico.
The riposte would be "firm" and "proportionate", and in line with WTO rules, Macron said.
As its first step to challenge the US tariffs, the European Union on Friday formally filed a request for consultations at the WTO.
Ross arrived in Beijing on Saturday morning for trade talks with Chinese officials, after the Trump administration renewed its tariff threats against China, and with key USA allies in a foul mood toward Washington after they were hit with duties on steel and aluminum.
Despite Trudeau's claim that Canada had reached an impasse with the U.S.in NAFTA talks, the official said the US would continue to pursue negotiations, acknowledging that a "range of issues remain".