Thousands protest dried-up river in Iran's Isfahan: state TV
The massive protest, that drew in farmers and other people from across Isfahan province, was the biggest since demonstrations over the water crisis started on November 9.
"Thousands of people from Isfahan, farmers from the east and west of the province, have gathered in the dry Zayandeh Rood riverbed with one key demand: let the river run," a state television journalist in Isfahan reported, broadcasting live images of Friday's rally.
Footage aired on the channel showed men and women in a crowd spanning the riverbed clapping in unison. "Plundered for 20 years" and "the water must return", they chanted.
The city of Isfahan is Iran's third largest, with a population of around two million.
It is tourist magnet due to its heritage sites, including a historic bridge that crosses the Zayandeh Rood river -- which has been dry since the year 2000 apart from brief periods.
Drought is seen as one of the causes, but farmers also blame the authorities' diversion of the river water to neighbouring Yazd province.
The Iranian government has promised to come to the aid of farmers and resolve the crisis.
"I have ordered the ministers of energy and agriculture to take immediate steps to deal with the issue," Iran's First Vice President Mohammad Mokhber said on television.
Energy Minister Ali-Akbar Mehrabian apologised to farmers for being unable to provide water for their crops.
"We hope to fill these gaps in the coming months," he said.
Iran's President Ebrahim Raisi had already met with representatives from the provinces of Isfahan, Yazd and Semnan on November 11 and promised to resolve water issues.
Largely arid Iran has been suffering chronic dry spells for years.
In July, deadly protests broke out in the southwestern province of Khuzestan after drought led to widespread water shortages.