"Saif was not the first choice. Imran was supposed to do it but he was not sure if he wanted to do it at that point of a time," Adajania told in an interview.
Being produced by Saif's Illuminati Films, the film will come out July 13.
"As Saif is the producer, he was going through the scripts, he read it and loved it. So, it worked out pretty well and that is how he came on board," he said.
Adajania debuted as a director with dark film "Being Cyrus" and it had Saif in the lead role. Dimple Kapadia and Boman Irani too featured in it.
For "Cocktail" too the director has roped in Dimple-Boman to play prominent roles.
Explaining their presence in the cast, he said: "Dimple and Boman are also there in the film and it is not like they were in 'Being Cyrus' so are part of this film as well. It is not a matter of familiarity but using talented actors who fit the bill."