European Commission President Jean-Claude Juncker responded with a list of threatened tariffs on U.S products, lamenting: "This is basically a stupid process".
"Secretary of Commerce Wilbur Ross will be speaking with representatives of the European Union about eliminating the large Tariffs and Barriers they use against the United States of America".
"Not fair to our farmers and manufacturers".
Fox criticised the unilateral imposition of U.S. tariffs, which will impose a 25 per cent duty on steel imports and a 10 per cent tax on aluminium imports, and said that they "have weak foundations in worldwide law".
"I told the president that imposing tariffs on steel and aluminum does not help with regard to NAFTA..."
"He only explained the schedule and the procedures", he said.
Jeff Flake, a Republican senator from Arizona and vocal Trump critic, on Monday introduced a bill in Congress to nullify the tariffs, though it would be extremely hard for the measure to achieve a two-thirds majority needed to override an expected Trump veto.
She warned that no one could win a "race to the bottom" and said the tariffs could risk "hurting everyone".
European steel and aluminum associations have warned that the USA tariffs could cost their sectors thousands of jobs.
The Commission said it expected to be in contact with Washington over the metals tariffs this week, but that no formal talks had been scheduled.
The negotiations between the European Union and the USA are to win an exception for Europe from the tariffs, with Brussels seeking clarity on how to achieve that.
Trump and his trade officials have signalled in the past they are looking for more access to Canada's dairy market within a renegotiated NAFTA deal.
Dutch Finance Minister Wopke Hoekstra said the tariffs are "a bad idea".
The president has said he favors fair and balanced trade partnerships and has floated the idea of reciprocal tariffs, which would tax other countries' imports at levels similar to what USA exports face.
Prime Minister Justin Trudeau dispelled that notion in a phone call to the president on March 5, followed by numerous calls to business and congressional leaders including the heads of the both houses of Congress.
Trump in turn has suggested that if the Europeans boost tariffs on US products he would impose new levies on popular German cars exported to the U.S. Seko also said these exports had made key contributions to USA industries and jobs, the statement said without elaborating. Indeed, most European Union countries are in North Atlantic Treaty Organisation, the world's biggest security alliance, together with the United States.