The US action, which takes effect at midnight (2pm AEST), cast a long shadow over a meeting of finance ministers from the Group of Seven top economies, which opened in Canada.
International Monetary Fund chief Christine Lagarde, warned of an erosion of trust. "It's going to distort and damage and disrupt supply chains which have been established now for decades," she said.
Ross, however, said inconclusive talks with the EU had failed to convince Washington that it should continue exempting the trading bloc from the tariffs - 25 percent duties on steel and 10 percent on aluminum - that it imposed in March.
Washington also is removing exemptions for Mexico and Canada because, he said, negotiations to revise the North American Free Trade Agreement are "taking longer than we had hoped" and there is no "precise date" for concluding them.
A presidential proclamation confirmed the action.
The White House maintained that since the tariffs were first imposed in March, they have had "major, positive effects on steel and aluminum workers and jobs and will continue to do so long into the future."
It said the administration's actions "underscore its commitment to good-faith negotiations with our allies to enhance our national security while supporting American workers."
But instead of dialogue, the announcement immediately set off threats of matching sanctions from Mexico, Canada and the EU.
Not a gunfight
Canada announced $16.93 billion (AUD) in retaliatory duties on US goods.
EU chief Jean-Claude Juncker said the 28-nation bloc "will announce in the next coming hours counter-balancing measures" in response to the US action.
Brussels previously threatened to slap tariffs on US products including bourbon, motorcycles and blue jeans.
Mexico said it will impose retaliatory duties on a variety of US goods, including steel and a host of agricultural goods, including pork, apples, blueberries and various cheeses.
"World trade is not a gunfight at the O.K. Corral," French Economy Minister Bruno Le Maire warned, referring to a 1957 western movie.
"It's not everyone attacking the other and we see who remains standing at the end," he said, declaring that the stiff US duties were "unjustified, unjustifiable and dangerous."
German Chancellor Angela Merkel said the EU would respond in a "firm and united" manner to the tariffs.
Meanwhile, South Korea negotiated a steel quota, while Argentina, Australia and Brazil have arranged for "limitations on the volume they can ship to the US in lieu of tariffs," Ross said.
Talks can continue
Despite weeks of talks with his EU counterparts, Ross said the United States was not willing to meet the EU demand to be "exempted permanently and unconditionally from these tariffs."
"We had discussions with the European Commission and while we made some progress, they also did not get to the point where it was warranted either to continue the temporary exemption or have a permanent exemption," Ross said.
Ross downplayed the threats of retaliation, and said talks can continue even amid the dispute to try to find a solution.
And he said Trump has the authority to alter the tariffs or impose quotas or "do anything he wishes at any point" - allowing "potential flexibility" to resolve the issue.
Trump imposed the steel and aluminum tariffs using a national security justification, which Ross said encompasses a broad array of economic issues -- a premise derided by US allies.
Ross said Trump was living up to his campaign promises.
"The overwhelming objective is to level the playing field," Ross said, adding that US goals include getting rid of trade barriers, protecting intellectual property and stopping forced technology transfers.
Protecting technology is the key issue in the US trade dispute with China, which the White House said will face 25 percent tariffs on $50 billion in goods.
Ross said he plans to travel to Beijing Friday for further talks aimed at finding a solution to the trade friction.
The administration had said the China tariffs were on hold, but then reversed course this week and announced it was planning to go ahead with them after all.
The US action prompted an outcry from Trump's own Republican party, although metal industry groups expressed support.
"When it comes to unfairly traded steel and aluminum, Mexico, Canada, and Europe are not the problem -- China is," said Kevin Brady, chairman of the House Ways and Means Committee.
Republican Senator Ben Sasse was more blunt: "This is dumb."