The White House on Sunday condemned Iran for using "lethal force" against demonstrators during unrest that left two dead and saw authorities arrest dozens and restrict internet access.
"The United States supports the Iranian people in their peaceful protests against the regime that is supposed to lead them," White House press secretary Stephanie Grisham said in a statement quoted by AFP.
"We condemn the lethal force and severe communications restrictions used against demonstrators," she added.
The unrest erupted on Friday, hours after it was announced that the price of gas would rise to 15,000 rials per liter (12 US cents) from 10,000 for the first 60 liters, and to 30,000 rials for any extra fuel bought after that each month.
Access to the internet was restricted a day after the demonstrations broke out.
A policeman was shot in a clash with "rioters" in the western city of Kermanhshah on Saturday and died the following day, provincial police chief Ali Akbar Javidan said, according to IRNA state news agency.
Several people were also wounded and dozens arrested in the demonstrations that saw motorists block highways and others torch public property.
Iranian Interior Minister Abdolreza Rahmani Fazli told state TV on Saturday that security forces will act to restore calm if the protesters “damaged public properties”.
On Sunday, Iranian Supreme Leader Ayatollah Ali Khamenei expressed support for the increases in gas and fuel prices, saying the protests against the move were encouraged by Iran’s enemies.
Iran's economy has been battered since May last year when US President Donald Trump withdrew the United States from a 2015 nuclear agreement and reimposed crippling sanctions.
In response to the US withdrawal from the nuclear deal and its imposition of sanctions, Iran has gradually scaled back its compliance with the 2015 deal.