The Rohit Dhawan-directed movie also stars his younger brother Varun and actress Jacqueline Fernandez in the lead roles.
"Nargis is doing a cameo in the film. She is doing a guest appearance. She will shoot for it once the dates are worked out keeping in mind John's injury," sources said, without divulging details about her role in the film.
Nargis, 36, earlier worked with John in Shoojit Sircar's 2013 film 'Madras Cafe' and romanced Varun in David Dhawan's 'Main Tera Hero' (2014).
Gossip mills are abuzz that superstar Akshay Kumar will also do a cameo in 'Dishoom'. His spokesperson was unavailable for a comment on it.
Rohit's directorial debut 'Desi Boyz' had Akshay and John in the lead.