Kasab was the lone surviving Pakistani terrorist responsible for the 2008 terrorist attacks that killed 166 people. He was hanged in November last year.
"I think that cinema has changed. Sanjay Dutt also did a negative character in 'Agneepath' (remake). The biggest challenge for me was that people should not tell me that I looked like Kasab that's why I got the role," Sanjeev told IANS.
He further added that it's important for an actor to convince his audience with his acting skills, rather than the way he looks.
"The face is similar, but if acting is not strong, you can't convince people. So according to me, my look is my luck. But to convince people, I had to be a strong actor," he said.
"The Attacks Of 26/11" released March 1.
Talking about the response to the film, Sanjeev said that people were liking him but hating his character.
Originally a theatre actor, it took him eight years to get a film.
"Eight years ago, I started theatre in Delhi. In 2008, I came to Mumbai. I didn't get work for four years. I gave audition for the film and I was selected within one-one-and-a-half month," he said.