"But I'm going to make her follow me (on Twitter) just by keeping talking about it.''
Bieber is dating fellow singer Selena Gomez and has spoken about what he looks for in a woman. He is a fan of curvaceous singers, explaining there is another star whose body he admires.
"I think I'm a butt guy. I just like butts. I'm attracted to them,'' he said. "Do I have any favourites? Nicki Minaj has got a nice one."
Bieber is known for having crazy fans who follow him everywhere and he admits finding it strange that some of his younger admirers seem so infatuated with him.
"I don't really agree with 12-year-olds talking about those inappropriate things,'' he said.
"I just think the younger people are, the closer the parents should watch out over the kids. But once they turn 13, it's easier because they're going to learn that stuff anyway.''