Protesters clashed with security forces in south-western Iran late Sunday, a day after several demonstrators were injured in nighttime skirmishes over water pollution, Iranian state media reported.
The latest protests were held in Abadan, 12 kilometres from Khorramshahr, where 11 people were hurt on Saturday when an unidentified gunman opened fire during a demonstration, according to officials. Abadan is home to Iran's biggest oil refinery.
State-run Irna news agency did not specify how many people were involved in the Abadan demonstration, but said security forces had broken up a crowd that was "disrupting public order".
It said people protesting over poor water quality in a western district of the city had thrown projectiles and set fire to rubbish bins and a vehicle.
The agency did not report any further injuries, but added that water pollution in the two cities of Khuzestan province had sparked several demonstrations over the past four days.
The province was devastated by the eight-year war between Iran and Iraq in the 1980s and suffers from chronic pollution and drought.
It has a largely Arab population that has long complained of official discrimination.
Iran has been facing mounting economic woes since the United States in May pulled out of a 2015 accord between Tehran and world powers that had lifted international sanctions in exchange for curbs on the Islamic republic's nuclear programme.
Iran's currency has plunged almost 50 per cent in value in the past six months against the US dollar and inflation is on the rise.
Traders in Tehran's Grand Bazaar held a rare strike on Monday against the collapse of the rial.
On Sunday, Vice President Eshagh Jahangiri said in statements broadcast on state television that Iran is suffering from several problems, not just US sanctions.
Among Iran's "woes", he cited its dependence on oil revenues along with a weak private sector and a fragile banking sector.