Chabahar lies in Sistan-Baluchistan province which has long been a flashpoint.
“This terrorist act led to the martyrdom of two members of the police force,” the province’s deputy governor in charge of security, Mohammad Hadi Marashi, told state television.
Chabahar city governor Rahmdel Bameri said earlier that four people were killed and many more wounded when the bomber blew up a car, but later revised the death toll to two.
“The explosion was very strong and broke the glass of many buildings close by,” Bameri told state television.
Many nearby shop owners and civilian passers-by, including women and children, were severely wounded, he added.
Chabahar lies some 100 kilometres (60 miles) west of the Pakistan border and is home to a large, mainly Sunni Muslim ethnic Baluchi community which straddles the two countries.
The number of assailants was not immediately clear.
“The terrorists tried to enter Chabahar police headquarters but they were prevented by the guards and they detonated the car bomb,” Marashi said without elaborating on how many assailants took part.
Chabahar has a deep-water port on the Gulf of Oman and with Indian assistance Iran has been developing it as a major energy and freight hub between Central Asia and India, bypassing Pakistan.