Section 145 of The Indian Penal Code, 1860 View Chapter 8

Joining or continuing in unlawful assembly, knowing it has been commanded to disperse.

Whoever joins or continues in an unlawful assembly, knowing that such unlawful assembly has been commanded in the manner prescribed by law to disperse, shall be punished with imprisonment of either description for a term which may extent to two years, or with fine, or with both.