Major indexes in Europe were also down broadly, with the CAC 40 in France and the Xetra Dax 30 in Germany declining by more than 2 percent. The Stoxx Europe 600 index saw nearly every sector decline on Friday.

At a meeting with industry executives on Thursday, Mr. Trump said he would formally sign rules enacting tariffs of 25 percent on steel and 10 percent on aluminum next week, surprising some of his closest advisers, who had urged him not to pursue such measures.

The proposed measures angered many of the United States’ closest allies and neighbors.

Jean-Claude Juncker, the president of the European Commission, said on Thursday night, shortly after the comments by Mr. Trump, that the tariffs appeared to represent “a blatant intervention” to protect the United States steel industry. He vowed the bloc would not “sit idly while our industry is hit with unfair measures that put thousands of European jobs at risk.”