Similar restrictions banning the assembly of four or more people have been clamped in Jammu and Kashmir's northern towns of Sopore, Baramulla and Bandipora.
Although police officers try avoid using the word 'curfew' for the restrictions, no pedestrian or vehicular movement is being allowed in the areas.
The Kashmir University has postponed all examinations scheduled for Friday. An official said new dates would be announced later.
Hardline separatist leader Syed Ali Geelani and the Jammu and Kashmir Liberation Front have asked people to stage protests on Friday against the hanging of parliament attack convict Afzal Guru.
They also want the government to hand over Afzal Guru's body, now buried in Delhi's Tihar Jail, to his family.
Authorities fear violence after the Friday prayers in "sensitive areas" of the city.
Director General of Police Ashok Prasad said no one will be allowed to breach the law.
Police and Central Reserve Police Force (CRPF) personnel have been deployed in the affected areas.
Coils of concertina wire have been placed to block traffic intersections in Old Srinagar to block passage of pedestrians and vehicles.