The attack, which took place outside the High Court in the Indian capital, forced the abandonment of the planned event.
The Jab We Met star took to Twitter to condemn the attacks in Delhi, saying: "Sad sad sad. Unacceptable. terrorists are the worst of all living things ....... We need to deal with them extremely strongly."
This is the third time that the film's producers have had to cancel key promotions.
The scheduled music launch in the UK was abandoned following last month's London riots.
A tribute to Michael Jackson in New York by lead star Kapoor was later abandoned due to Hurricane Irene.
The actor has spent over two years working solely on the movie, directed by his father Pankaj Kapur.
The project has encountered a number of problems during filming. Extras working on the production in Scotland told local media they had not been paid.
Kapoor is also said to have suffered an accident on-set and an outdoor location suffered extensive damage in a fire.
Mausam releases September 16.