In an interview with NBC's "TODAY," she again called the president's tweet a "sexist smear" said she interpreted it as sexually suggestive.
"Well, certainly that's how I and many people read it, and it was certainly a sexist smear intended to silence me. ... I'm not going to be silenced on this issue," Gillibrand said.
Gillibrand on Monday called for Trump to step down because of numerous sexual misconduct accusations against him, becoming one of multiple members of the Senate Democratic caucus to say he should at least consider resigning. If Trump does not step down, Gillibrand said, Congress should investigate his conduct.
The president wrote that "lightweight" Gillibrand used to come to his office "begging" for campaign contributions. The senator "would do anything for them," he said.
White House spokeswoman Sarah Sanders on Tuesday denied that Trump's tweet was sexist and said he has expressed a similar sentiment about men in the past. She said Trump was "not alleging anything" and only commenting on corruption in the political system.
Gillibrand on Wednesday again called on Trump to resign amid a national reckoning over sexual harassment.
"If you put that in the context of multiple accusers who have accused him of sexual assault and sexual harassment, that are credible, you need accountability, and I think what people do want is accountability and he should resign," the senator said.
"And if he's unwilling to, Congress should investigate," Gillibrand added.
On Tuesday, Trump called the accusations "false" and "fabricated."