Hours after Robert S. Mueller III, the special counsel, broke his silence and said that Russia had sought to damage Hillary Clinton’s presidential campaign, Mrs. Clinton said that the “systemic efforts to interfere” in the 2016 election “deserves the attention of every American.”

Mrs. Clinton made the remarks as part of a commencement address on Wednesday afternoon to more than 2,400 Hunter College students inside New York City’s Madison Square Garden. Amid a sea of purple caps and gowns, she also leveled fresh criticism at the Trump administration for what she said was its “complete refusal to condemn a foreign power who attacked our democracy” and its failure to protect the country’s voting systems against future attacks.

“It seems absolutely clear that we’ve got to deal with what has been investigated and reported,” she said.

Earlier in the day, Mr. Mueller held a 10-minute news conference — his first public characterization of the investigation since it began more than two years ago — in which he discussed central elements of his report, including the decision to not explicitly clear President Trump of obstruction of justice.