The 19-year-old star said she would happily peel off for the cameras, because she was proud of her "good genes."
But Keira who appeared in Pirates Of The Caribbean said she would not pose for a magazine shoot.
She said, "I don't have a problem with nudity in films. I'm not saying that i'd strip off at every opportunity and run around screaming.
"But I think sometimes it's needed. Sometimes it can be very beautiful and it gets a point across in a very powerful way.
"But I don't think I'd feel particularly comfortable spreading my legs and wearing a very small bikini for a lads' mag."
She added, "In Hollywood you have to be strong and confident about your body shape."
Keira's latest film King Arthur hits UK cinemas on July 30.
