WASHINGTON—President Donald Trump told lawmakers Tuesday that he is eyeing “tariffs and/or quotas” as a way of restricting U.S. imports of steel and aluminum on national-security grounds, but he acknowledged concerns that blocking metal imports could lead to price increases for U.S. industries that use the metals.

“We cannot be without a steel industry, we can’t be without an aluminum industry, and so what we’re talking about is tariffs and/or quotas,” Mr. Trump said at a meeting with Senate and House lawmakers.

...