The 17-year-old, who has recently been criticised for her attitude, insisted that she doesn't care what people say about her.
She explained: "It's about owning it no matter what anyone says. This is who I am and this is who I am going to be. It's about every girl being true to themselves.
"I smoke, so what? Why do people give a s**t what a 16-year-old girl who they've never met does? It's not like I'm sitting there going, 'Kids, you should go buy a pack of cigarettes'.
"When I walk outside with a cigarette and someone takes a picture of it and puts it on the internet, it's not my problem. I'm just living my life and I'm not gonna live my life for other people."
Momsen added that she does not read any negative press about her.
"I don't read that cr*p that describes me as having an attitude, but I don't know why that's a bad thing. I didn't get into this to be a role model for 7-year-olds. I have no interest in doing that," she said.
"If parents don't like some of the stuff I do then they shouldn't let their kids watch me."