Rallies swept the Iranian capital for a second day on Monday with demonstrators protesting the deteriorating economic situation.
They swarmed the historic Grand Bazaar, forcing shopkeepers to close their stalls.
On Sunday, protests forced two major shopping centers for mobile phones and electronics to close in Tehran.
Iran's semi-official ISNA news agency described the protests as erupting after the Iranian rial dropped to 90,000 to the dollar on the country's black market, despite government attempts to control the currency rate.
Videos posted to social media showed protesters at the bazaar heckling shopkeepers who refused to close, shouting in Farsi: "Coward!"
Others chanted “death to the dictator.”
Special police forces have since cordoned off the parliament building at Baharestan Square to impede the protesters’ advance.
Videos posted on social media showed demonstrators confronting the police.
The footage showed tear gas in the air and protesters screaming, "They attacked us with tear gas!" Another man is heard shouting: "Come back!"
Iran's latest economic troubles come against the backdrop of international firms pulling away from the country after President Donald Trump's decision to withdraw America from Tehran's nuclear deal with world powers.
At the end of last year, similar economic protests roiled Iran and spread to some 75 cities and towns, becoming the largest demonstrations in the country since its 2009 disputed presidential election.
The protests in late December and early January saw at least 25 people killed and nearly 5,000 people arrested by authorities.
