The EU took the U.S. to the World Trade Organisation to challenge the legality of the new tariffs and the Trump administration's national security justification.
And Mexico said it would impose retaliatory duties on a variety of USA goods, including steel and a host of agricultural goods such as pork, apples and cheese.
"The problem is that by taking that kind of unilateral action the U.S. is undermining the principle of multilateralism in worldwide trade, so it becomes more hard to deal with other concerns ― like trade and market access practices in China", Dombrovskis said in an interview.
"Everyone expressed their complete incomprehension of the American decisions and everyone said it was up to the Americans to take the next step since they were the ones who imposed the tariffs".
But in the case of Canada and Mexico, he said the decision was based on making progress in the ongoing North American Free Trade Agreement talks, and there is no resolution in sight.
The European Union has formally set in motion its trade retaliation against the United States over tariffs, filing on Friday a request for consultations at the World Trade Organization. "So now this door for the moment is closed".
Bruno Le Maire, France's minister of the economy and finance, said the US tariffs are "unjustified, unjustifiable and risky". Trade war fears drove Chinese shares lower on Friday, with the Shanghai Composite Index ending down 0.7 per cent.
Mr Trump originally imposed the tariffs in March, saying a reliance on imported metals threatened national security.
Canadian Prime Minister Justin Trudeau said the Trump administration's argument that the tariffs were necessary for national security reasons was an "affront" to Canada, which has fought alongside the U.S.in numerous armed conflicts.
Malmstrom said over-production from China, not Europe, was to blame for the glut of steel that prompted the U.S. action.
Dr Fox said he would speak to U.S. commerce secretary Wilbur Ross about the situation again on Monday.
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Barr's tweet came one day after she compared President Barack Obama's former staffer Valerie Jarrett to an ape. In the tweet Barr said Jarrett was "a cross between the Muslim Brotherhood and the "Planet of the Apes ".
The Trump administration wants China to buy more United States goods to lower a trade deficit.
"The world we live in is much more nuanced than that and supply chains can be quite complex".
"We have a huge problem with the American government, with the White House", Moisi said.
The impact of the tariffs will likely be "small", only affecting 0.8 per cent of annual Canadian output, TD senior economists said in a note.
Such facts, he said, show how Trump's view of trade is overly simplistic.
According to, the current trade trend is destroying the USA steel and aluminum sectors. "At the same time, most of his product is made out of aluminum, and there is great uncertainty as to what the tariffs do to actually the price of his core product".
"We have some issues between us, we discussed them at length over the last years and obviously this will continue to be issues we will address", the EU's High Representative for Foreign Affairs, Federica Mogherini, told the same press conference.
But as part of the efforts to address outstanding trade disputes, Europe will present a complaint before the World Trade Organisation against China's intellectual property practices, it confirmed on Friday.
Meanwhile, the OECD says threatened new trade barriers and rising oil prices could hurt long-awaited global economic growth.
In a clear reference to Trump, Macron added: "These solutions might bring symbolic satisfaction in the short term". Dombrovskis reiterated the European Union position during the G7 meeting.
"I think there was a comment out there that (this was) the G6 plus one". Ross will also meet the German and French economy ministers.