Hillary Clinton on Friday rejected the F.B.I.’s assertion that she had been “extremely careless” with classified material as secretary of state, offering her first public comments on the matter since the Justice Department closed its inquiry without bringing charges against her this week.

In interviews on CNN and MSNBC, Mrs. Clinton tried to put the controversy surrounding her use of a private email server to rest, brushing off a rebuke from James Comey, the F.B.I. director, who had criticized her for being negligent.

Although Mr. Comey, in a congressional hearing on Thursday, pointed out several contradictions between what Mrs. Clinton had said publicly about her email use and what she said in sworn testimony, Mrs. Clinton insisted Friday that she did not intentionally send or receive any classified information through her private account. She also appeared to be spreading the responsibility to her State Department staff.

“I think there are about 300 people in the government, mostly in the State Department, but in other high positions in the government with whom I emailed over the course of four years — they, I believe, did not believe they were sending any material that was classified,” Mrs. Clinton said on CNN. “They were pursuing their responsibilities. I do not think they were careless.”