WASHINGTON — Kirstjen Nielsen, the homeland security secretary, said on Tuesday that she did not believe that Russia had tried to help President Trump during the 2016 election — putting her at odds with American intelligence agencies that found widespread meddling by Moscow.

Speaking to reporters after briefing Congress on voting security, Ms. Nielsen said she believed that Russia had tried to sow confusion on both sides of the political divide.

“I do not believe that I’ve seen that conclusion that the specific intent was to help President Trump win,” she said. “I’m not aware of that.”

Ms. Nielsen was on Capitol Hill with Christopher A. Wray, the F.B.I. director, and Dan Coats, the director of national intelligence, in a closed-door meeting to brief lawmakers about efforts to protect American voting systems from hacking in the coming midterm elections.