Police drove through the streets of Srinagar, the main city, ordering residents to stay indoors. Despite the curfew, clashes and protests broke out in several places, police said.
Troops did not allow Friday prayers at main mosques in areas under the curfew, including Srinagar's Jamia Majid, for fear that worshippers would carry out protest marches afterward. However, residents were able to offer prayers at smaller neighborhood mosques.
The restive Himalayan region was rocked by violent anti-India protests after Mohammed Afzal Guru was hanged Saturday in a New Delhi jail and buried there. Guru had been convicted of involvement in a 2001 attack on India's Parliament that killed 14 including five gunmen.
Many in Kashmir believe Guru did not receive a fair trial, and the secrecy with which the execution was carried out fueled anger in a region where anti-India sentiment runs deep.
A curfew has been in place since the execution, but groups of demonstrators have defied it and clashed with government forces. Three protesters have been killed and more than 100 have been detained, according to police.
The curfew was relaxed in some areas in recent days, but was restored ahead of Friday prayers in the Muslim-majority region.
Protesters, chanting "We want freedom" and "Return Guru's body," were stopped by police and paramilitary soldiers. In some places troops fired tear gas and rubber bullets to disperse rock-throwing demonstrators, a police officer said on condition of anonymity because he was not authorized to speak to the media. At least one man was injured.
The All Parties Hurriyat Conference, an umbrella organization of separatist political and religious groups, called for a mass funeral prayer for Guru to be held Friday at a large square near Srinagar's Martyr's Graveyard, where hundreds of separatists and civilians killed in the region's long-running conflict are buried.
In New Delhi, dozens of Kashmiri students gathered to protest Guru's hanging and demand that his body be returned to his family.
Insurgents have been fighting in Kashmir for more than two decades, demanding either a separate state or merger with Muslim-majority Pakistan. The region is divided between India and Pakistan and is claimed in its entirety by both.