"The electricity shortage and the cuts will multiply before the start of summer," Energy Minister Parviz Fattah was quoted as saying by the Mehr news agency.
He said there was a shortfall in electricity production due to "the drought and the lack of water" in dams.
"The production of hydro-electric power must reach 6,500 megawatts but for the moment it is only 1,500 megawatts."
A spring of only sporadic rain has left Iran with a severe drought as it enters summer, which is normally hot and dry all over the country except in the humid northern provinces.
Supreme leader Ayatollah Ali Khamenei has already told Iranians to watch their consumption of water. Officials have said a drop of 10 percent in consumption is needed to prevent even worse cuts.
The capital Tehran and other cities have already been hit by cuts of up to three hours in certain areas as the authorities seek to make-up the shortfall.
Iran had to cope with major power cuts during the 1980-1988 war with Iraq but since the 1990s the authorities have invested in major projects, such as hydroelectric dams, to match the consumption of its over 70 million population.
The electricity cuts recall major gas cuts suffered by northern Iranian towns during the bitterly cold winter this year, as a halt of gas exports to Turkey failed to make up for the domestic shortfall.
Iran, OPEC's number two oil producer which also sits on the second largest global gas reserves, has said it needs nuclear power to meet the energy needs of a growing population when the fossil fuels run out.
But this is disputed by the West, which accuses Tehran of being more interested in developing a nuclear weapon, a charge it vehemently denies.
