The 24-year-old said she had read too many of "the same" scripts, in which women languished in the shadows or were simply there to help the male lead.
She criticised the "t**ts out there (in the film world) who don't deserve to be in the positions they're in and treat people like s**t", it was reported by the Press Association.
She told GQ magazine: "I've nearly walked off very big films before, and I would, because I don't want that in my life. I want to enjoy the work I do."
The actress said that now she is established, she wants to work with people who respect her: "I'm looking at working with people I get on with, that respect me, that don't just see me as a piece of a*s. Which I have experienced as well."
Gemma has just returned from Paris, where her latest film Tamara Drewe has opened after being a hit at the Cannes Film Festival. She said of her time in the French capital: "There are pictures of me everywhere in those f*****g hot pants.
"It's weird and still baffling, but I see it as not me. It's the character. That's how I get my head around it."
Do you agree with Gemma about Hollywood's obsession with looks and sexist attitude?