Rohit features in the film as a baddie, who is being chased by Hrithik Roshan's blind character to seek revenge.
When director Sanjay Gupta narrated the film to him, Rohit was "blown away with the premise" but was hesitant to sign the film.
"When he narrated me my role, I said no to the film. I said I can't do it, and he was taken aback too. I was worried because in 20 years of my acting career, I've never done this kind of role," Rohit told PTI.
"It could have gone either way. It is not only evil but very lecherous. After being here for so many years, then not being able to pull it off would've been bad. It was a matter of confidence."
The 48-year-old actor, however, did come on board later for the project which would feature him alongside his elder brother Ronit Roy.
Pointing out that both of them have different working techniques, Rohit said, "Ronit puts in a solid amount of hard work. He researched for the role. He had a tutor who worked with him and prepared for the Marathi twang. I am completely different actor from him. I went to the set blank, only knowing the lines. Hopefully, you'll see it work on the big screen."
The action-thriller features Hrithik as a blind man, who avenges the death of his girlfriend, enacted by Yami Gautam.
Rohit says having Hrithik as a co-star was an absolute delight, as the "Bang Bang" actor is selfless and caring.
"A lot of credit goes to Hrithik. While filming he made sure my confidence was at another level. Whether it was rehearsing for the fight sequences, doing them, he took extreme care.
"There was a shot where he hits me and I had a dead fall. But there was no crash mat that day. He didn't give the shot unless a crash mat was arranged. He then called for his own and then gave the shot," Rohit adds.
"Kaabil", produced by Rakesh Roshan, is scheduled to release on January 25.