It is the first time Mrs. Clinton has publicly addressed the impact of the hacks since the intelligence community concluded that they were specifically aimed at harming her campaign.

“Make no mistake, as the press is finally catching up to the facts, which we desperately tried to present to them during the last months of the campaign,” Mrs. Clinton told the group, which collectively poured roughly $1 billion into her effort. “This is not just an attack on me and my campaign, although that may have added fuel to it. This is an attack against our country. We are well beyond normal political concerns here. This is about the integrity of our democracy and the security of our nation.”