ISLAMABAD, Pakistan — Pakistan on Sunday deployed army troops in Islamabad to help restore law and order to the capital, officials said, a day after violent clashes between Islamist protesters and the police left at least six people dead and 200 others injured.

The move came after the prime minister and army officials held emergency talks and agreed troops would be sent to protect vital areas and buildings like the Parliament, the prime minister’s house and the diplomatic enclave that houses embassies in the capital.

The military told the governing party, Pakistan Muslim League-Nawaz, that it would safeguard only important national buildings and installations and would not use lethal force to quell the protesters, according to the terms of the deployment in a letter that was shared with The New York Times and circulated by the local news media.

According to a military spokesman, Maj. Gen. Asif Ghafoor, the army chief, Gen. Qamar Javed Bajwa, had urged Prime Minister Shahid Khaqan Abbas on Saturday “to handle the protest peacefully, avoiding violence from both sides as it is not in the national interest.”

The military also sought clarification from the government on why nearly 8,000 police officers and members of a paramilitary force had failed to quell a protest that has blocked a main entrances to Islamabad for more than two weeks.

An uneasy calm prevailed in Islamabad on Sunday, a day after thousands of police officers fired tear gas and rubber bullets in an unsuccessful attempt to move about 2,000 supporters of an Islamic cleric, Khadim Hussain Rizvi, who have paralyzed the capital by camping out on a main highway in a blasphemy row with the government.

The authorities said dozens of police officers and paramilitary troops were among the 200 injured as stone-throwing crowds fought with the police for control of the intersection.

The clashes spread to other cities, mainly in Punjab Province, as supporters of Mr. Rizvi took to the streets and blocked main thoroughfares and highways, setting up a major crisis for the governing party, Pakistan Muslim League-Nawaz.

Mr. Rizvi has accused the country’s law minister, Zahid Hamid, of committing blasphemy after the governing party proposed a new version of an oath to be taken by lawmakers that dealt with a declaration of Prophet Muhammad as God’s final prophet.

The law minister denied the charge, releasing a video in which he emphatically stated that he believed that Muhammad was God’s final prophet. The government reversed the changes in the oath. But the efforts to placate Mr. Rizvi and several other religious leaders failed, and demonstrations began three weeks ago.

On Sunday afternoon, supporters of Mr. Rizvi roamed about the Faizabad Interchange, one of the main entrances to the capital from Rawalpindi and suburbs, with an air of victory.

That protesters had managed a day earlier to repulse the advance of the police forces appeared to have emboldened them. As the standoff has escalated, protest leaders have stepped up their demands; they are now calling for the entire cabinet to resign.

“Government used all kinds of force and thousands of personnel, but by the grace of Allah, they ran like rats when the believers of the Prophet Muhammad retaliated,” said one protester, Muhammad Zubair.

Abid Hussain, a seminary leader, who was leading a group of around 100 protesters, said, “We will avenge the martyrdom of our six fellows by continuing the protest.”

The aftermath of the clashes was visible in the charred grass on the sidewalks and burned tents that the protesters had pitched earlier in the month. Boxes of food and plastic bottles of water were scattered on the ground.

As a helicopter flew overheard, dozens of protesters turned their eyes toward the sky, raised their arms and shouted, “I am here, O Prophet of God, I am here,” a defining slogan of Mr. Rizvi’s party, Tehreek-e-Labaik Pakistan.

About 2,000 people gathered at the protest site and offered funeral prayers for those killed in Saturday’s clashes.

Residents from neighboring towns and cities, who said they wanted to show solidarity with the protesters, streamed to the protest site to join the sit-in.

Twitter, Facebook and YouTube remained inaccessible on Sunday. Many television news networks that had been taken off the air resumed broadcasts; a regulator had banned live coverage of the police operation for fear it was inflaming religious sentiment.

Blasphemy remains highly controversial in Pakistan, often leading to violence and mob justice. In recent years, hard-line Islamists have killed two prominent politicians who advocated changes in the country’s laws.

On Saturday, protesters stormed the home of Mr. Hamid in Pasrur in Sialkot District. He was not there at the time. Another lawmaker from the governing party, Mian Javid Latif, was injured in an attack by protesters in Sheikhupura District, local news outlets reported. Local news outlets reported that protesters in Rawalpindi had damaged the entrance of the house of Nisar Ali Khan, a former interior minister.

The latest spasm of violence has raised concerns about the stability of the government of the governing party, which is already weakened from the disqualification of its leader, Nawaz Sharif, in July.

Political analysts say that the current turmoil will worsen if the government does not take a political initiative to calm the unrest. For now, the authorities have deployed rangers and members of a paramilitary force to some parts of the capital.

The Islamabad high court ordered the government last week to clear the interchange. But the sit-in continues.

Ihsanullah Tipu Mehsud contributed reporting.