"I don't remember anybody telling me that they wanted to give a boob job to the poster, so I'm glad they didn't," Fox News quoted Knightley, as telling Pop Tart.
Knightley also said that off screen she doesn't feel the need for enhancing her chest and is very proud of it.
"I'd love to say that I was really strident and went "absolutely not" if they'd asked to enhance my breasts. But I don't remember it ever coming up, which is rather nice," she said.
It has also been reported that Knightley was more than willing to set her hair ablaze for her act in the flick.
"I think the insurance people said, 'You've shot half the movie, and if she goes up in flames then we're not going to be able to finish it. So you're not allowed, So it is actually computer graphics," Knightley said.
Knightley, who is portraying the role of a mother in the flick revealed that the motherly feeling didn't get on to her head.
"I don't want one (a child) thanks. I'm all right," she said with a laugh. "Never say never, but right now I'm fine. Thank you very much," she said.