"Sat next to a journalist from the NYT last night who told me 'Melania is a hooker.' Whatever your politics it's crucial to call this out for what it is: slut shaming. I don't care about her nudes or sexual history and no one should," Ratajkowski wrote in a series of tweets Monday.
Ratajkowski, who catapulted to stardom following her semi-nude appearance in the "Blurred Lines" music video and as Ben Affleck's student-turned-lover in the movie "Gone Girl," actively campaigned for Bernie Sanders during the 2016 primary.
While she tweets frequently about Democratic issues, she also speaks out about women's issues, weighing in on nudity in an interview with InStyle UK
"'It's weird to me that the reaction to a woman's naked body is so controversial in our culture. My mum taught me to never apologise for my sexuality. My dad never made me feel embarrassed. I also don't think I've ever had an awareness of my own body as being super-sexual. It was always just my body," she said.
"Gender specific attacks are disgusting sexist bullsh**," she tweeted Monday.
The first lady took to Twitter herself Monday evening to thank Ratajkowski for her display of girl power, writing, "Applause to all women around the world who speak up, stand up and support other women! @emrata #PowerOfEveryWoman #PowerOfTheFirstLady."
Bernstein, who writes features for the Times, is the son of CNN contributor and former Washington Post reporter Carl Bernstein and the late Nora Ephron. He made a documentary about his mother's career, "Everything is Copy," which aired on HBO last year.
"Speaking at a party in what I thought was a personal conversation, I nevertheless made a stupid remark about the first lady," Bernstein tweeted Tuesday afternoon. "My editors have made it clear my behavior was not in keeping with the standards of the Times, and I agree."
He added, "My mistake, referring to unfounded rumors, shouldn't reflect on anyone else and I apologize profusely."
While she has not yet defined her platform as she settles into her new role as first lady, Trump has said advocating for women and speaking out against cyberbullying are top priorities.
"It will be my honor and privilege to serve this country. I will be an advocate for women and for children," she said
in a rare campaign trail appearance in Berwyn, Pennsylvania, days before the election. "It is never OK when a 12-year-old girl or boy is mocked, bullied or attacked. It is terrible when it happens on the playground, and it is absolutely unacceptable when it is done by someone with no name hiding on the Internet. We have to find a better way to talk to each other."
The office of the first lady did not immediately respond to CNN's request for comment.