She was taken to her hotel room and given first aid, media reports said.
The incident occurred when Aishwarya had to ride a bicycle for a particular scene. While practising for it, the actress's ghaghra (skirt) got entangled in the cycle chain and she lost her balance, smashing into a "No Parking" board. Her co-star in the film is Abhishek Bachchan.
Shooting for the film has been put on hold.
A few years ago, Aishwarya had hurt herself while shooting for "Khakee".