Rapper Chris Brown has been ''having fun'' with pop star Rihanna but insists their relationship is nothing serious.

Brown, who has an on-off relationship with model Karrueche Tran, says that he is enjoying his relationship with his former girlfriend, who he was convicted of assaulting in 2009.

''We're friends. Nothing too serious... We're not trying to start a life together right now, we're just having fun," contactmusic.com quoted Brown as saying.

It was believed "Drunk Texting", a track on the 25-year-old star's new album "X", is about Rihanna, and while Chris insists it isn't, he doesn't mind theories being shared because he thinks it encourages record sales.

Asked if the track is about Rihanna, he said: ''Oh no, not at all. I think that's just the fans' perception or the media's perception at all times because of our history. But whenever we do music, people can make the assumption and that's fine because if they buy more because they think that, then go ahead and buy a thousand copies.

''But as far as me writing and going into that, I don't really try to put my focus on Rihanna every song. At the end of the day it's almost six, seven years later. It's like, how many more times am I going to talk about the same situation?''