According to the state news agency Irna, "armed terrorist elements" on two motorcycles fired at protesters and security forces at a market.
In addition to the dead – three men, a woman and a girl – the attackers left at least ten injured people behind.
No one has claimed responsibility for the attack.
Iran has been rocked by protests - "riots" according to authorities - since September 16, when 22-year-old Mahsa Zhina Amini died in the custody of hardline morality police where she was taken for violating the country's strict dress code for women.