The actor will be playing a Haryanvi boy in the upcoming film from director Vishal Bhardwaj.
He told IANS: "During the first script reading of the film, I was unable to say the Haryanvi dialogues. It was not easy, I felt I made a big mistake and I should back out.
"When I told [Vishal Bhardwaj] I won't be able to do it, he said he was sure I could. He had faith in me, even when I didn't.
"The role is different. It required a lot of preparation for almost two and a half months. I have always felt that the more we rehearse, the better we perform.
"[Bhardwaj] was very calm on the set and guided all the performers. Even if something was not working out, he would find a way to make it work. He knows the right way to do things."
The director added: "I wanted to see Matru in Imran. I had liked him in Delhi Belly but I wanted to do more. He was very patient with me and we finally achieved the look."
Matru ki Biljee Ka Mandola is an adaptation of best-selling novelist Chethan Bhagat's 2 States.
The drama centres on a couple from different states whose parents disapprove of their marriage.
It was reported in June that rising star Arjun Kapoor had replaced Khan in the lead role.
Watch the trailer for Matru ki Biljee Ka Mandola below: