The actress is to be replaced by Tamil-Telgu star Samantha Ruth Prabhu.
A source told the Mumbai Mirror: "At this point in her career going southwards for Sonam would give the wrong signal to the filmmakers in Bollywood.
"Mani had his heart set on Sonam since she suited the young, innocent, effervescent, sophisticated girl's role to the hilt. He had to look for a last-minute replacement.
"Gautham [Manon] wanted Samantha for the Hindi version of Vinaaithandi Vaaruvaaya. Having failed in that endeavour, he is now in the process of completing Assi Nabey Poore Sau as a Hindi launch vehicle for her."
The Bollywood film will see Prabhu and co-star Aditya Raj Kapoor play a pair of lovers from their teenage years to their mid-twenties.
Sonam Kapoor will next be seen playing an ambitious young reporter in Bollywood film Herogirl.
The 26-year-old this week denied that she would be having a Barbie doll made of her, like fellow stars Kareena Kapoor and Katrina Kaif.