Portman spoke out at the Women's March in LA on Sunday.
The Women's March took place on the anniversary of Trump's inauguration. Thousands of women gathered in many cities across the world for the second Women's March.
Many celebrities attended the marches. Natalie Portman attended and gave a speech to the crowd, in which she recalled her experiences of being objectified as a 13-year-old in Hollywood.
She spoke about her first film, 'The Professional'. She was just 13 when the movie was released.
"I opened my first fan mail to read a rape fantasy that was written about me. A countdown was started on my local radio show to my 18th birthday, euphemistically the date it would be legal to sleep with me. Movie reviewers talked about my budding breasts in their reviews."
"I understood very quickly, even as a 13-year-old, that if I were to express myself sexually that I would feel unsafe. And that men would feel entitled to discuss and objectify my body to my great discomfort."
Watch the full speech here;