Commissioner Makran, Bashir Bangulzai, said that the mortar shell landed on a vehicle, instantly killing Kam Jan, a resident of Washuk, and causing extensive damage nearby.
Jan was travelling in the vehicle. His body was shifted to a local hospital.
"We have informed provincial and federal governments about the Iranian violation," Bangulzai said.
Security forces reached the site of the attack and cordon off the area. They have started a probe into the incident.
The attack came a week after Iranian border guards fired five mortar shells into Pakistani territory.
Iran accused that militants hiding in Pakistan were involved in the attack.