EU trade commissioner Cecilia Malmstrom set out plans to retaliate against the proposed U.S. tariffs.
These include higher import duties on bourbon, peanut butter, cranberries, orange juice, steel, and industrial products, she said.
On Tuesday, Donald Trump’s top economic advisor Gary Cohn, who opposes tariffs, resigned.
That was after Mr. Trump said E.U. trade rules make it “impossible” for U.S. firms to do business with the bloc.
“We have serious doubt about that justification. We cannot see how the European Union, friends, and allies in NATO, can be a threat to national security in the U.S.,” she said.
“We find that assumption deeply unjust.”
She added: “We have made clear that if a move like this is taken, it will hurt the European Union, it will put thousands of European jobs in jeopardy, and it has to be met by a firm and proportionate response.”
She also said the E.U. was “intensively talking” to U.S. counterparts to try to persuade Washington “to have a rethink”.