Dozens demonstrated on Monday at a rally in the Iranian capital Tehran against power cuts amid a drought, state TV reported, with some people chanting "political" slogans.
The protest follows others over water shortages that began more than 10 days ago in the south-west, where at least four people have been killed, Iranian media reported.
In central Tehran, a "limited gathering" began before noon when some shop owners at the Aladdin and Charsou malls, two of the main mobile and tech markets, marched down Jomhouri Street to "protest problems caused by power cuts", state TV reported.
"At the same time, a group tried to use the dissatisfaction and make it political" by chanting "norm-breaking slogans", it said.
The term "norm-breaking" is regularly used by Iranian media to refer to slogans critical of the authorities.
A video posted on Twitter by the ultra-conservative Fars news agency showed protesters blocking the busy street, with security troops on motorcycles near by.
Fars said the gathering comprised "about 50 people".
Their chants included "Neither Gaza nor Lebanon, my life for Iran" and "Police, support us", the video showed.
Iran does not recognise Israel, and support for the Palestinian cause and groups such as Lebanon's Hezbollah has been a pillar of its foreign policy since soon after its 1979 revolution.
A power company spokesman told Fars that Aladdin mall had been notified before a two-hour power cut caused by "excessive use".
About 4pm on Monday there was a police presence around Aladdin mall but traffic appeared to be normal and power had been restored, AFP reported.
Rolling power cuts began in Tehran and other large cities this month, with officials blaming them on the effects of drought on hydroelectric power generation, and surging demand.
There have been fewer cuts in the capital since the first week of July, when unannounced blackouts lasted for hours.
But the Energy Ministry still notifies people ahead of planned cuts because of an overburdened grid.
There have also been protests over water. The south-western province of Khuzestan has been gripped by drought since March, with protests about water shortages in towns and cities since July 15.
Iranian media and officials have reported at least three people killed in the province, including a police officer and a protester.
"Opportunists" and "rioters" were accused of shooting at demonstrators and security forces.
State TV reported a fourth person killed on Thursday in the western province of Lorestan, where people took to the streets "on the pretext of water problems in Khuzestan".
Khuzestan is home to a large Arab minority and its people regularly complain of marginalisation.
In 2019, the province was a hotspot of anti-government protests that also shook other areas of Iran.
Over the years, blistering summer heatwaves and sandstorms from Saudi Arabia and neighbouring Iraq have dried up Khuzestan's once fertile plains. Scientists say climate change exacerbates droughts.
This month, President Hassan Rouhani said the drought was "unprecedented", with average rainfall down 52 per cent compared with the previous year.
Iran has in recent years been hit by several protests over the economy and living conditions made worse by punishing US sanctions reimposed since 2018.
Iran, also battling the Middle East's worst Covid-19 outbreak, on Monday marked its second daily infection record within a week, with 31,814 new infections reported in 24 hours.