The epicenter of the quake, which hit at a depth of 10 kilometers, was Nosrat Abad city, 100 kilometers northwest of the provincial capital Zahedan.
There have been no initial reports of damage or casualties as a result of the earthquake.
A day earlier, at least four people were killed and more than 120 others were injured in a 5.0-magnitude earthquake in the northeastern Iranian city of Kashmar in Khorasan Razavi province.