Khamenei told state television that the government is raising petrol prices in order to provide additional subsidies to low income families.
Iran’s supreme leader Ayatollah Khamenei has defended petrol price rises that have prompted widespread protests across the country.
Khamenei told state television that some of those taking part in the demonstrations were enemies of the republic, carrying out sabotage and arson.
An unknown number of people are believed to have died in street clashes in dozens of cities across the country; the death of at least one policeman has been confirmed by state media.
Despite the 50 percent rise, at eight litres for one euro petrol prices in Iran are still among the cheapest in the world.
But the protests are reported to have become political, and internet observers are reporting that networks are running so slow that it amounts to a shutdown.
The government says it is raising petrol prices in order to provide additional subsidies to low income families.