Ryan said he would continue to urge the president to focus the tariffs only on countries that violate trade law, like China.
The administration is still working out exemptions from the tariffs of 25 percent on steel imports and 10 percent on aluminum before they take effect in two weeks.
The president was surrounded by steel and aluminum workers as he explained his decision at a White House ceremony.
Chairman of the Senate Finance Committee Orrin Hatch, a Republican from Utah, has expressed his opposition to the Trump tariffs.
The tariffs, set to take effect in 15 days, do not apply to imports from Canada and Mexico so that US officials can assess progress as they renegotiate the North American Free Trade Agreement.
Since Trump suggested the tariffs earlier this week, opining that "trade wars aren't so bad", Republicans on Capitol Hill have been trying frantically but unsuccessfully to talk him out of it.
In the Senate, Republicans are opposing the duties en masse, with Senator Jeff Flake already preparing a bill to "nullify these tariffs".
His comments in a Cabinet meeting Thursday come hours before a 3:30 p.m. meeting to formalize the tariffs amid uncertainty in the West Wing over which countries will be exempted from the protectionist measure. "This is very hard, I think, to address by legislation, and it's obvious the president certainly has his mind made up", Roberts said.
Brown is not the only Democrat championing Trump's tariffs.
"A strong steel and aluminum industry are vital to our national security - absolutely vital".
Even some of Trump's most ardent defenders seemed ready for a fight. Both said they are continuing to lobby the president to change course. It is the biggest break in Republican unity during the Trump administration so far. "History has proven that the unintended consequences of tariffs are vast and serious, and the ones announced today threaten to undermine our growing economy and the relief that millions of Americans are feeling as a result of tax reform". Metal industry trade groups in China called for retaliation, targeting imports ranging from "stainless steel and electronics to coal and farm products", as Market Watch reported. And it's a recipe for killing growth.
All of the heartburn was created by Trump's radical and hasty trade announcement. Self-delusion is a powerful toxin, but it's no excuse for having backed and defended an economic illiterate.