The EU took the USA to the World Trade Organisation to challenge the legality of the new tariffs and the Trump administration's national security justification.
"We tried to do it through negotiation and we will now do it by standing together and formulating a common European answer, possibly working more closely with Mexico and Canada", he said, adding he hoped this would make Trump rethink.
Separately, the US and European Union have lodged WTO disputes challenging China's technology transfer policies. "By people representing us who didn't have a clue", he said at the time.
Trump had offered the two US neighbors a permanent exemption from the steel and aluminum tariffs if they agreed to USA demands on NAFTA.
The EU plans to tax things like whiskey and Harley motorcycles as it strikes back at the US.
France's finance minister, Bruno Le Maire, called the USA tariffs "unjustified, unjustifiable and risky".
Stock prices slumped amid fears of a trade war, with the Dow Jones Industrial Average falling almost 252 points, or 1 percent, to 24,415.84.
The Trump administration has given permanent metals tariff exemptions to several countries including Australia, Argentina and South Korea, but in each case set import quotas.
While the USA administration's decision to hit its European and North American allies with the metals tariffs was not aimed directly at China, it also sets the background for negotiations with Beijing, where Ross was headed on Friday for talks. "That Canada could be considered a national security threat to the United States is inconceivable".
The U.S. action widens a rift with America's closest allies, threatens to drive up prices for companies and consumers that buy steel and aluminum, heightens uncertainty for businesses and is already alarming investors in global financial markets.
U.S. Commerce Secretary Wilbur Ross met with his European counterparts in Paris this week, but was unwilling to bend on any demands.
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Trump's Trade Policies 'Completely Backwards': Tariffs Won't Bring Jobs to US
Talks with Europe had "made some progress" but not enough for additional exemptions, he said in a conference call from Paris. He reiterated the US concerns over the indirect flow of cheap Chinese steel into the USA through other countries.
The U.S. tariffs coincide with - and could complicate - the Trump administration's separate fight over Beijing's strong-arm tactics to overtake U.S. technological supremacy.
"The world we live in is much more nuanced than that and supply chains can be quite complex". "We are ready to rebuild this multilateralism with our American friends", he said.
Canada and the USA are closely integrated trading partners and Thursday's moves could cripple industries, including the auto sector, where supply chains are interconnected and goods pass back and forth across the border several times before they are finished. Other nations could copy the US move.
Such facts, he said, show how Trump's view of trade is overly simplistic.
Janzen said the steel and aluminum tariffs are a unique result of Trump policies whereas softwood lumber has been an irritant for decades.
"Over the long run, these tariffs will drive aluminum prices higher globally, increasing the cost of beer production for all brewers".
Meanwhile, the OECD says threatened new trade barriers and rising oil prices could hurt long-awaited global economic growth.
"Obviously, the visit didn't happen", he said.
"Our steel and aluminium industries are hugely important to the United Kingdom, but they also contribute to U.S. industry including in defence projects which bolster USA national security", she said. But German Economy Minister Peter Altmaier insisted the Europeans were ready to negotiate special trade arrangements, notably for liquefied natural gas and industrial goods, including cars.
U.S. Treasury Secretary Steven Mnuchin speaks at a news conference during a meeting for the G7 Finance and Central Bank Governors in Whistler, B.C., on Saturday, June 2, 2018.