The protests started in southwest Khuzestan(Iran) province and spread to the nearby city of Aligoodarz in western Lorestan province.
People have been demonstrating for more than a week over water shortages during Iran's worst drought in over half a century that has affected households, agriculture, livestock farming, and led to power blackouts.
One witness, who was at a protest in Khuzestan province, told CNN that people were shot dead by anti-riot police and security agents, and that a continued heavy security presence remained in Khuzestan on Saturday.
The dissident Human Rights Activists News Agency (HRANA) on Saturday reported that at least 10 people died in the protests and an unknown number of people were injured.
At least 102 people have been arrested in the past 10 nights in 30 cities and towns across Iran, according to HRANA.