The project, titled Bloody Veer, is directed by first-time filmmaker Heeraaz Marfatia.
A source told the Hindustan Times: "It's a light-hearted funky venture and one could say it's the coming together of Wake Up Sid and Twilight. It is about hip youngsters and a gang of friends. It's a fun film with a dash of humour and romance.
"Ranbir has not done this kind of a role, and is pretty excited about playing a vampire and is going through the script."
In March, top Bollywood choreographer Remo D'Souza said that Kapoor should star in a dance film to show off his talents.
However, it was reported in the same month that the actor was cancelling his worldwide tour, where he would have teamed up with former co-stars to perform numbers from his previous films.
Watch Kapoor in the official trailer for Rockstar: