The case against Kumar was filed by Anil P Nayar, a social worker.
Mr Nayar says the unbuttoning of the jeans during show time was really "vulgar and indecent".
"After the preliminary inquiry, we will register a case against Akshay Kumar, [his wife] Twinkle Khanna, the abettor of the Lakme Fashion Week show and the top management of the Grand Hyatt [the hotel where the show was held] and we will take action against them," news agency Reuters quoted SG Pandey, a lawyer of the complainant, as saying.
Police say they have received the complaint, but are yet to register a case.
"They gave an application, it is under inquiry and after inquiry, we will let you know," the agency quoted senior police officer Nissar Kalambole as saying.
Dressed in a T-shirt and denim jeans, Kumar walked up to wife Twinkle, seated in the front-row, and asked her to undo the top button of his jeans.
Kumar has made a name for himself by playing lead roles in action and comedy films.
His film, Singh is Kinng, was one of the biggest hits of 2008.
In 2007, he appeared in several hits, like Namastey London, Heyy Babyy, Bhool Bhulaiyaa and Welcome.
Recently, he was awarded Padma Shri, India's civilian award for eminent people.