Four policemen were killed on Sunday fighting Kurdish separatists near the town of Urmia in Iran's western borderlands.
Tension has been simmering among Iran's Kurdish minority since last month when rioting erupted in the town of Mahabad. Shortly after those riots, three policemen were killed in a gunbattle with separatists near the town of Oshnavieh.
Officials said on Sunday the unrest had spread to the Kurdish town of Saqqez, where two people died and 145 were arrested during demonstrations in which state buildings and banks were damaged.
Iranian authorities say all seven policemen who died fighting separatists in the last two months were killed by fighters from a group called Pezhak.
Security experts say Pezhak is an Iranian wing of the Kurdistan Workers Party, whose separatist struggle has regained momentum in southeast Turkey after it called off a unilateral ceasefire last summer.
It was not immediately clear whether any Kurdish fighters were killed in the gunbattles in Iran.
Iranian officials insist the latest violence is not ethnically motivated but Kurdish leaders disagree, saying Tehran's discriminatory treatment of their people is stirring the unrest.
A recent UN report suggested that Tehran was discriminating against its religious and ethnic minorities in the provision of basic amenities.
Iran's 67 million population includes about six million Kurds, many of whom live in the mountainous northwest bordering Iraq and Turkey, also home to Kurdish minorities.