Himanshu Roy, joint police commissioner, said that security, including additional police numbers and check-points, had been increased around the city.
Mr Roy said: "The men are planning violent attacks that are going to cause destruction.
“We believe the threat is serious.”
Two of the terrorists, allegedly linked with Lashkar-E-Taiba, were killed by Indian commandoes as they attempted to end the rampage. Only one was caught alive and earlier this year was sentenced to death.
Although Lashkar-E-Taiba is officially banned in Pakistan, in July the Indian Home Secretary accused Pakistan of masterminding “from beginning to end” the attacks.