Three "terrorists" and three members of the Iranian security forces were killed during night-time clashes along Iran's border with Pakistan, state news agency IRNA reported on Tuesday.
"At 0130 this morning (2100 GMT Monday], a terrorist group from Pakistan attacked" a police post in the border area of Mirjaveh, around 75 kilometres southeast of Zahedan, the capital of Sistan-Baluchistan province, IRNA said.
Three of the attackers were killed along with a police officer and two members of the Revolutionary Guards, it added.
Iran has criticized Pakistan in the past for supporting the Jaish al-Adl jihadist group, which it accuses of ties to Al-Qaeda and carrying out numerous attacks in Sistan-Baluchistan.
The restive province is poor and home to a population that is predominantly Sunni and ethnic Baluchi, in a country where 90 percent are Shiite and two-thirds are Persian.
From 2005 to 2010, Sistan-Baluchistan suffered a prolonged insurgency by the Balochi-Sunni militant group Jundallah, meaning "soldiers of Allah", although violence was largely curbed after the killing of its leader in mid-2010.