The firefight occurred on Friday in the southeastern province of Sistan and Baluchistan, near the border with Pakistan.
At this stage, it is unclear whether the clashes could be linked to the widespread wave of protests that erupted in the country after 22-year-old Mahsa Amini died in police custody on 16 September.
According to state media, a colonel in the military Revolutionary Guard must also have been killed in the clash.
The impoverished province has previously seen sporadic fighting between Iranian government forces and various militant groups.