In the romantic thriller, KJo plays a villain called Kaizad Khambatta, who has a flamboyant character.
"I am really nervous about it because it's my first foray into acting," the filmmaker, who did a small role in Yash Raj Films "Dilwale Dulhania Le Jayenge", said here.
"I am really stressed out about how it is going to be accepted when it is out," he added.
Although, the stylish filmmaker wears black normally, he was made to wear all colours in the film. And he could not throw tantrums even courtesy "Bombay Velvet" director Anurag Kashyap. He feels Kashyap is "a person you can't hold tantrums with".
"I wear lot of black but I have worn all kinds of colours in the film. I just kept my mouth shut because I felt that as an actor I can't have the perspective because I have to follow the vision of the filmmaker, and that's what I want from the actors myself," said Johar, who was present at the cover launch of Filmfare's Glamour & Style Issue.
"I couldn't throw tantrums on the sets and Anurag is somebody you can't hold tantrums with because he has a clear vision," he added.
Also starring Anushka Sharma and Ranbir Kapoor, "Bombay Velvet" is set for release on May 15.