Dunham, the 26-year-old creator and star of HBO's 'Girls' said the 'Diamond' hitmaker's behaviour isn't something young fans should try to emulate, reported Us magazine.
"[Fame is] an amazing thing and it's a platform that you have to take seriously. Which is why sometimes, it's like...
"I used to be really into Rihanna, that pop star, and then it's like -- again, I don't want to ever throw stones from my glass house -- but I follow her on Instagram and I just think about how many little girls beyond what I could even comprehend are obsessed with Rihanna," said Dunham.
"Like, you know, she left Barbados, she's had this amazing career, she's won a Grammy... She's talented. And then she gets back together with Chris Brown and posts a million pictures of them smoking marijuana together on a bed. And it cracks my heart in half in a way that makes me feel like I'm 95 years old," she added.
The TV star, meanwhile, said she's "had to become more conscious about what I say and what I promote, not in a way that stifles me, but just in a way where I realise now that there are 17-year-old girls who come up to me and tell me that the show means a lot to them."