The actress told her Mausam co-star that his image requires updating, Mumbai Mirror reports.
"Shahid and Sonam have got along very well. Shahid has been teasing Sonam, calling her a 'fashionista'. She took her title very seriously and has been pulling Shahid's legs over his casual clothing," a source revealed.
Sonam, who played a brand-obsessed Delhiite in Aisha, suggested a stylist friend for the actor.
"Sonam introduced him to Kunal Rawal, who is a close friend. Rawal will now design the clothes for the actor in Kunal Kohli's yet untitled film," added the source.
The official music launch of the Pankaj Kapur production was delayed recently due to the London riots.
The romance-drama is scheduled to premiere at this year's Toronto Film Festival.
The stars of Mausam are also reported to be attending a special screening of the film in Feltham, London on September 14, with a theatrical release two days later.