The EU would take "all necessary measures" to respond if the USA did impose tariffs, Mr Le Maire warned.
Mr Stace said the EU should activate "safeguard measures" to prevent European markets being disrupted by a surge of as much as 25 million tonnes of steel diverted from the US.
The Trump administration has demanded that Beijing make concessions and threatened to punish it for allegedly stealing USA technology by imposing tariffs on $50 billion of imports from China.
"The EU is a peace project, including on trade", she said, pointing to the numerous trade agreements the EU is signing.
"I was visiting a factory in Northeast Ohio and the manager of the product line was pointing out to a series of tires that used to be imported from overseas, now being brought in the United States because of the tariff that was imposed a year ago, and he was very excited about the fact that the product came back to the United States", he says.
British Prime Minister Theresa May said she was "deeply disappointed" and reiterated a call for Britain and the European Union to be "permanently exempted" from the "unjustified" metals tariffs.
When asked whether a trade war has already started, Dombrovskis said: "That is certainly not the vocabulary we are using, we keep our communications channels open. we need to push for a solution on this particular issue".
The key difference between then and now, European trade experts say, is tone.
The federal government announced Thursday afternoon that it would impose some $16.6 billion in dollar-for-dollar counter-tariffs on a wide variety of United States goods - everything from whiskey to sleeping bags to quiche - that will take effect on Canada Day.
Maude urged the European Union to avoid a "tit-for-tat" response and instead stick "robustly to free trade".
"This is stupid. It's counterproductive", former British minister of state for trade Francis Maude told the BBC. "Any government that embarks on a protectionist path inflicts the most damage on itself".
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"The inevitable result of putting these tariffs on imports will be to increase prices on consumer goods for its own citizens".
The initial tariffs were announced in March after President said that the U.S. had been unfairly treated in trade with its neighboring and oversees partners.
But hope faded when US Commerce Secretary Wilbur Ross announced that the United States would impose tariffs of 25 percent on steel and 10 percent on aluminum from Canada and others from Friday.
Faced with thin margins, automakers will have to make a hard choice: Pass along the 25 per cent tariff on steel and 10 per cent rate on aluminum and risk getting stuck with inventory, or absorb the increases and reduce profits, said Flavio Volpe, president of the Automotive Parts Manufacturers' Association.
Canada and the US 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.
In addition to Volkswagen vehicles, the company produces Audi, Porsche, and multiple other brands.
Foreign Affairs Minister Chrystia Freeland, who pushed the steel and NAFTA issues during her meeting on Tuesday in Washington with USA trade czar Robert Lighthizer, has also made it clear that Canada would retaliate if the duties are imposed.
French President Emmanuel Macron has told U.S. President Donald Trump that the new U.S. tariffs on European, Mexican and Canadian goods are illegal and a "mistake".
And Macron pledged the retaliation would be "firm" and "proportionate" and in line with World Trade Organization rules. He said he planned to travel to China on Friday for trade talks between the world's two biggest economies.
The U.S. decision came despite last-minute talks in Paris this week to try to reach a deal.