Section 144 of the Code of Criminal Procedure (CrPC) was imposed in Barhaj area of Deoria district in Uttar Pradesh after a 25-year-old man was allegedly beaten to death by some men on Janmashtami.
Section 144 of the CrPC prohibits the assembly of more than four persons in an area.
District Magistrate Amit Kishor said the restrictions would remain in force till September 15.
Sumit was injured when he tried to save his father from the alleged attackers, who were enraged over the objection to loud music during the festival.
The incident had taken place on Saturday night in Barhaj's Patel Nagar, police said.
"On the occasion of Krishna Janmashtami, some youths were playing DJ in Patel Nagar of Barhaj on Saturday night. Munnu Lal asked them to stop it, which enraged 10-12 youths," Deoria SP Shripati Mishra said.
"They attacked Munnu Lal with sticks. When his sons Sumit and Sachin, along with his wife Sanju Devi, rushed to save him from the attackers, they too were beaten up," the SP added.
Police reached the spot and admitted the injured to the local health centre, where doctors referred Munnu Lal and Sumit to the district hospital for treatment.
Sumit (25) was declared dead by the doctors at the district hospital, the SP said, adding they are trying to arrest the accused.