Anti-government protests were held in the Iranian capital and the western city of Kermanshah on Friday, a day after similar protests in the country's north-east.
About 300 demonstrators shouted slogans including "Political prisoners should be freed" and "Freedom or death" before riot police broke up the protest in Kermanshah, the main city in a region where an earthquake killed over 600 people in November.
A smaller protest was staged in Tehran against price hikes and president Hassan Rouhani's economic policy, the semi-official ILNA news agency reported.
UAE Minister of State for Foreign Affairs Dr Anwar Gargash tweeted: “The protests in Mashhad and other Iranian cities are an opportunity [for Iran's government] for rational review, to put their internal interests ahead of Tehran’s quests in the Arab region."
He added: "The interest of the region and Iran lie in internal construction and development, not in antagonising the Arab world."
Videos posted on social media showed demonstrators yelling, "The people are begging, the clerics act like God".
In Kermanshah, the protesters destroyed public property, the semi-official Fars news agency reported.
Meanwhile, ILNA quoted the security deputy of Tehran's governor, Mohsen Hamedani, as saying that fewer than 50 people gathered at a public square in the capital, and that all but a few of them left after a police warning. "A few of them were temporarily arrested," Mr Hamedani said.
The outbreak of unrest reflects growing discontent over rising prices and alleged corruption, as well as concern over the country's costly involvement in regional conflicts such as Syria and Iraq.
On Thursday, hundreds took to the streets of Mashhad, Iran's second city in the north-east of the country, shouting slogans mostly directed at Mr Rouhani's government for failing to tackle a range of economic problems.
The head of Mashhad's revolutionary court, Hossein Heidari, said on Friday that 52 people were arrested for chanting "harsh slogans", Fars reported.
"We consider protest to be the people's right but if some people want to abuse these emotions and ride this wave, we won't wait and will confront them," Mr Heidari said.
Videos published by a small reformist media group, Nazar, showed people in Mashhad chanting "Death to Rouhani".
More provocatively, there were also chants of "Death to the dictator" and "Not Gaza, not Lebanon, my life for Iran" - a reference to anger in some circles that the government is focusing on the wider region rather than improving conditions at home.
Prominent conservative cleric Ayatollah Ahmad Alamolhoda, the representative of supreme leader Ayatollah Ali Khamenei in Mashhad, called earlier for tough action against the protests.
"If the security and law enforcement agencies leave the rioters to themselves, enemies will publish films and pictures in their media and say that the Islamic Republic system has lost its revolutionary base in Mashhad," Irna quoted him as saying.
He said a few people had taken advantage of Thursday's protests against rising prices to chant slogans against Iran's role in regional conflicts.
Tehran backs Syrian president Bashar Al Assad in his country's civil war, Shiite militias in Iraq, Houthi rebels in Yemen and Lebanon's powerful Hizbollah group.
However, Ali Vaez, Crisis Group's Iran Project Director, noted on Twitter that public opinion has "limited influence" when it comes to shaping Tehran's regional policy decisions.
Mr Vaez added that he felt it was unlikely that Iran would turn its back on its regional allies in a bid to placate the protesters.
Similar yet smaller protests reportedly took place in a few other cities on Thursday, responding to calls on the Telegram messaging service for a day of demonstrations to say "No to high prices".
Egg prices have doubled since last week due to the government's culling of millions of chickens diagnosed with avian flu, government spokesman Mohammad Bagher Nobakht told reporters on Tuesday.
But the reasons behind the protests go deeper, according to a local member of parliament.
"There is a major crisis in Mashhad caused by illegal financial institutions," Hamid Garmabi, who represents the city of Neyshabour near Mashhad, told Fars.
He was referring to the mushrooming of unauthorised lending institutions under former president Mahmoud Ahmadinejad between 2005 and 2013.
A poorly regulated banking sector combined with a construction boom left many credit companies stuck with toxic debts and unable to repay investors.
Mr Rouhani has sought to clean up the financial sector since he was first elected in 2013. His government has shut down three of the biggest new credit institutions - Mizan, Fereshtegan and Samen Al Hojaj - and he has tasked the central bank with reimbursing lost deposits, but progress has reportedly been slow.
Mashhad was one of the worst-hit areas by the closure of Mizan, which had around one million accounts, leading to several protests in the city since 2015, according to the official Irna news agency.
Other financial scams have also hit the region, notably the collapse in 2015 of a megaproject to a build the new town of Padideh next to Mashhad, which left more than 100,000 investors out of pocket.
"The shadow of stagnation in Mashhad and Khorasan Razavi province is more than other places in the country due to the unfortunate investment events in companies such as Padideh, Mizan Financial Institution and other credit funds," a senior housing official in the province told Irna last year.
Mr Rouhani’s signature achievement, a 2015 deal with world powers that curbed Iran’s nuclear programme in return for a lifting of most international sanctions, has yet to bring the broad economic benefits the government says are coming. This has added to the frustration among Iranian people, commentators noted.
Unemployment stood at 12.4 per cent in this fiscal year, according to the Statistical Centre of Iran, up 1.4 per cent from the previous year. About 3.2 million Iranians are jobless, out of a total population of 80 million.