The mortars hit Parom area of Panjgur district, according to a senior district official.
"The mortars were fired without any justification. So far we have not received any report about any human loss," he said.
Local Pakistani officials have lodged a protest with the Iranian border guards chief over the border violation.
Security of the area has been beefed up after the attack as additional troops were dispatched to Panjgur district.
Pakistan shares a 900-kilometre-long porous border with Iran, which has alleged that militants and smugglers often sneak into its territory from Pakistan.