Starring Ranbir Kapoor and Anushka Sharma, 'Bombay Velvet' was a period-drama which tanked at the box office.
"When a film fails, it is 100 per cent the director's fault. If 'Bombay Velvet' didn't work, it is entirely my fault. The director is the only one who has the power to say no," Kashyap told reporters here.
"A lot of the places where I should've taken a stand, I didn't. So the mistake is mine. When a film is good, it's everybody's contribution."
Kashyap, 43, was speaking at the trailer launch of his upcoming movie "Raman Raghav 2.0".
The 'Gangs of Wasseypur' helmer said directors need to often put their foot down and oppose anything which goes against the film they are making.
"What happens is, when you are making a film, you start it out and midway the process kind of changes. You forget why in the first place you wanted to make the film. A lot of the times we need to put our foot down and say 'no, this doesn't go with the film'. We give into a lot of pressure, we go on a back foot," he added.
Known for making small-budget independent films like "Black Friday", "Dev D", "Gulaal", Kashyap's "Bombay Velvet" was pitched as his biggest movie ever.
The 'Ugly' director said sometimes a film's budget becomes so huge that a director starts feeling the pressure. "When a film's budget becomes so huge that it is beyond your control, the pressure is so much that you go on the back foot. And that is the biggest mistake. However big a bowler is, (Virat) Kohli (cricketer) has to go in front and play. When you go backwards you hit the wicket," said.
'Raman Raghav 2.0' stars Nawazuddin Siddiqui as a serial killer while Vicky Kaushal will play the role of a troubled cop.
The film, slated to release on June 24, is inspired by Raman Raghav, also known as Psycho Raman, a psychopathic serial killer who terrorised the streets of Mumbai in the mid-1960s.
The movie will be showcased in the Directors' Fortnight sidebar at the upcoming Cannes Film Festival, which opens tomorrow.
