The Pakistani actor, who made his debut in Tere Bin Laden, has already starting shooting the untitled project in the UK.
Sunny Malik, Bollywood correspondent with Ishq, told Digital Spy: "Ali is currently filming with an up-and-coming actress in London.
"That's why he has been absent from the Mere Brother Ki Dulhan promotional events in India."
The Fox Star India project is reportedly set across three cities - Paris, London and New York.
Zafar, 25, will next be seen alongside Imran Khan and Katrina Kaif in love triangle romance Mere Brother Ki Dulhan.
The Yash Raj Films production releases worldwide September 9.