Bachchan, 73, and Aamir will share the screen space for the first time in the movie, to be directed by "Dhoom 3" helmer Vijay Krishna Acharya (Victor).
There were reports that post her latest release "Befikre", the actress was considered for the project.
"There have been reports of me doing 'Fan' also. It's all up in the air, all rumours," Vaani told PTI
The 28-year-old actress was recently seen in filmmaker Aditya Chopra's "Befikre", her second Hindi film after her debut movie "Shuddh Desi Romance".
Vaani says for her role as the free spirited, French born Indian girl Shyra, she received the best compliment from Chopra himself.
"My director thought I am the best Shyra he could ever have. That's the best compliment I got, coming from Adi it becomes all the more special. He said 'Even today if I have to look back, I can't see any other person be Shyra. For me you are Shyra for life'," the actress said.
Vaani, however, says she is aware that "Befikre" - which aimed to celebrate love in a carefree, fun-filled and impulsive spirit polarised the audience, but feels it was a well made film.
"Personally, deep down as a team we all loved the film. Ranveer (Singh), I, Adi, people who watched the screening before, we always got a good positive response. I feel it's a good happy film. It really confuses me when I am thinking why won't people like it," she said.
"It's a rom-com. I feel people are used to watching stories with drama and heightened dramatic conflicts, but this movie doesn't serve that...But there are also people who watched the movie twice or five times and did appreciate it," she added.