TEHRAN, Iran — The death toll in five days of anti-government protests in Iran climbed today as plainclothes police officers kept a close watch over a tense capital and President Hassan Rouhani continued to appeal for calm.

State media reported one police officer was killed and three others wounded in a shooting in Najafabad, in central Iran, that was blamed on "a person who wanted to create a disturbance." The killing brought to 13 the number of people killed since the unrest began Thursday, according to the Associated Press.

Security officers chased packs of demonstrators after dark along side streets of central Tehran. Near Palestine street, small groups of protesters, outnumbered by anti-riot police and paramilitary forces, set trash bins ablaze and shouted, "Death to the dictator!" and "I sacrifice my life for Iran!" — although few defied the heavy security presence to join them.

Rouhani told a meeting of Iranian lawmakers his government would take action against "a small minority" of demonstrators who he said had insulted the sanctity of the Islamic Revolution and damaged property.

But in an effort to assuage public anger, Rouhani acknowledged some who took to the streets in the largest unauthorized demonstrations seen here in years were suffering economically and their concerns should be heard.

"The enemy will not remain silent when faced with the Iranian nation's progress and greatness, but there are also deceived people among the protesters who have rightful demands," the president said, according to state-run Press TV.

Accounts posted on Iranian social media channels said police clashed with demonstrators in the southern town of Izeh who attempted to take over police and military installations, but state TV said security forces repelled the attacks.

Two people were shot dead there Sunday, lawmaker Hedayatollah Khademi told Iranian news agencies, but it was unclear whether the shots were fired by security forces or demonstrators.

The semiofficial Iranian Students News Agency reported today that Izeh was "quiet and tranquil now, and local officials are in control."

Iran's Interior Ministry said Rouhani had asked security forces not to repeat "the same tragic mistakes" of 2009, when authorities violently crushed an uprising that followed the disputed re-election of former President Mahmoud Ahmadinejad.

Although hundreds have been arrested since last week, and Iran has blocked access to the Instagram and Telegram social media apps to prevent protests from spreading, security forces have mostly have avoided using deadly force to put down demonstrations.

It was the second consecutive day Rouhani — a prime target of demonstrators frustrated with the two-term president's failure to deliver on promises of economic and social reforms — has broadcast a message of understanding via state media.

On Sunday, he was quoted as saying: "Criticism and protest are the people's rights, and they should lead to solutions to the country's problems."

But there was no immediate sign of how Rouhani's administration or the ruling Shiite Muslim theocracy would address the demands of a large and varied group of protesters who lack a coherent message or leader.

The rallies that began Thursday in the city of Mashhad in anger over rising prices and persistent unemployment have since spread to more than 25 cities and taken aim at the entire ruling establishment.

Protesters, including many young and working-class Iranians who are not part of the country's mostly educated opposition movement, have called for the resignations of Rouhani and of the supreme leader, Ayatollah Ali Khamenei. A Tehran police official said 90 percent of the protesters were younger than 25, according to Jamaran, a news agency close to the government.

A tall, broad-shouldered young protester standing in the subway station beneath Enghelab Square said Iran's security establishment had collaborated with Rouhani's hard-line opponents to start protests in Mashhad, but the demonstrations are "now out of their control."

"I don't know what will be the end of these cat-and-mouse chases ... ," said the protester, who would give only his first name, Ali. "But I know that if they calm down, which is possible, the hard-liners and President Rouhani will have to compromise on some social freedoms such as relaxing the Islamic dress code."

But he said the anger among Iranians was so deep that "on another occasion, under some other pretext, the riots will come back."

Khamenei has been silent since the protests began, but today's editions of Kayhan, a daily newspaper that is the mouthpiece of the supreme leader, carried a front-page headline calling for a heavy crackdown against "anti-establishment activists."

President Donald Trump weighed in on the protests again on Twitter, saying: "The great Iranian people have been repressed for many years. They are hungry for food & freedom." He also took aim again at the Obama administration for backing the 2015 nuclear deal, championed by Rouhani, that eased sanctions against Iran's economy, but has failed to bring about a broad-based recovery.

Israeli Prime Minister Benjamin Netanyahu also commented in support of the demonstrators, saying in a short statement on YouTube that the Iranian people "deserve better" than they have received under the current government. "I wish the Iranian people success in their noble quest for freedom," he added.