The American actress plays Kapoor's girlfriend in her debut Bollywood role in the political drama Rajneeti.
Thompson, 30, has already appeared in a string of American television dramas including The Sopranos.
In an interview with the Hindustan Times, she said: "When I met [director Prakash Jha] and he narrated the role of Ranbir Kapoor's American girlfriend to me I knew I had to do it.
"Before watching Prakashji's films I thought Bollywood meant singing and dancing. Here was a gritty realistic cinema that I certainly wanted to be part of."
She added that Kapoor and Jha have made her want to try her luck in the Indian film industry.
"Ranbir really took care of me. He made me feel so comfortable. Not for a minute did I feel like an outsider.
"If I've decided to make a career in Hindi cinema it's because of Ranbir and Prakashji who never let me feel like an outsider," she said.