The president’s downplaying of Russian involvement in the 2016 election comes as Facebook provides congressional investigators with more than 3,000 advertisements Russia purchased during the campaign and reports that the special counsel’s investigation was focusing in part on the president himself.

Mr. Trump’s allegation that the news media gave unfair coverage during the campaign echoes accusations Mrs. Clinton made in her recent book, “What Happened.” While Mr. Trump said the news media favored Mrs. Clinton, the former Democratic nominee said the news media did not focus enough on links between Mr. Trump and Russia.