The protests have flared in many of the same areas that experienced unrest two years ago, when demonstrators protested a similar proposal to slash state subsidies. Then, as now, lower-income Iranians rose up against a system that they said had failed them economically.

But a wider spectrum of society may have joined the revolt this time around, analysts say, pointing to demonstrations in major cities and at universities, including the University of Tehran. Protesters have also clashed with police in urban centers such as Isfahan, Mashhad, Shiraz and Tabriz.

Over the past two years, Iran's economy has worsened because of U.S. sanctions and declining oil sales - revenue the government uses to pay salaries and fund imports. Iran's economy is expected to contract by 8.7 percent this year, according to the World Bank.