A series of low-intensity blasts hit one of the poorest towns in the Sistan va Baluchestan province, near the Afghan-Pakistan border, early on Tuesday morning.
Three people were wounded in the explosions, the Islamic Republic News Agency said.
Provincial police commander Brigadier-General Nour Allah Younesi told journalists that the blast "broke the windows of three cars parked on the road and shattered glasses of houses in a 20-metre area".
The incident is under investigation by the police and security force in the area, he added.
On Sunday, up to eight people were killed in attacks in the Arab-dominated city of Ahvaz and the capital, Tehran, ahead of a fractious election campaign leading up to Friday's vote.
Judicial spokesman Jamal Karimi Rad said six suspects had been arrested on suspicion of involvement in the attacks, and one over the Tehran blast.
Officials have accused the Iraq-based People's Mujahidin, which is Iran's main armed opposition group, and Baathist supporters of deposed Iraqi president Saddam Hussein as well as "foreign agents".