According to the Hindustan Times, the Bollywood actor is determined to look good for her debut appearance at the event.
"Since Cannes Film Festival is the ultimate destination for style and fashion, I am putting in my best effort to look radiant on the red carpet," said Lamba. "I'm spending more time at the gym, besides having changed my diet intake."
The Bachna Ae Haseeno star added: "No girl will ever be satisfied with her weight and looks."
Lamba joins other Indian film actors Aishwarya Rai-Bachchan, Mallika Sherawat, Sonam Kapoor and Freida Pinto at the festival.
The actress will appear on the red carpet for Woody Allen's Midnight In Paris premiere on May 11.
The Hindi film celebrity recently questioned the political timing on the announcement of Osama Bin Laden's death.
> Lamba signs Shirish Kunder project