The unrest followed a day of violent protests in which at least 52 people were killed around the country on Friday.
Two protesters were killed and 17 people were wounded in the southern Iraqi city of Nasiriya. A group of protesters broke off from thousands gathered in central Nasiriya to storm the house of a local official, police said. Guards opened fired on the protesters after they torched the building, police said.
In Baghdad, security forces lobbed tear gas to try to disperse demonstrators in Tahrir Square. Of the 26 wounded, five people were in critical condition, after being struck directly in the head by tear gas canisters, police and hospital sources said.
Iraq's military and Ministry of Interior signaled in statements that they planned to respond more firmly to protests on Saturday.
Whereas tear gas was used only to repel those who approached the capital's fortified Green Zone on Friday, security forces were using it on everyone assembled in Tahrir Square on Saturday.
The Green Zone is the central government zone of Baghdad that was closed to the Iraqi public for many years.
"We came with just flags and water bottles, but they hit us," said 33-year-old demonstrator Silwan Nour. "We are peaceful, we have no weapons."
Tear gas canisters were thrown into the crowds roughly every 15 minutes, a Reuters correspondent said.
This further angerered a crowd that is protesting against the political elites they say have repeatedly failed to improve ordinary Iraqis' lives after years of conflict and economic hardship.
"Our demands are very simple but they can't even give us that. This is our country! Abdul Mahdi is just a figurehead. Baghdad will never be silent," said one protester.
Most of those killed on Friday were protesters, mainly in cities in the south of the country. Eight protesters were killed in Baghdad, most of them after being struck by tear gas canisters launched by security forces.
Protesters were better prepared on Saturday, distributing masks and homemade remedies to help guard themselves from the tear gas. Others handed out free food and water.
'STEALING FROM US'
In Iraq's mainly Shi'ite southern provinces, which saw violence overnight as protesters clashed with Iranian-backed Shi'ite militias, a heavy security presence on Saturday dissuaded large crowds from gathering. A curfew was still in place across most urban areas.
Parliament had been set to meet on Saturday in an emergency session to discuss protesters' demands, but it failed to reach a quorum and the session was canceled.
"The government has been stealing from us for 15 years. Saddam went and 1,000 Saddams have been hiding in the Green Zone," a young protester, who declined to be named, said on Friday, referring to the former Iraqi dictator.
The Interior Ministry praised what it called the restraint shown by security forces on Friday.
"The security forces secured the protection of demonstrations and protesters responsibly and with high restraint, by refraining from using firearms or excessive force against demonstrators," it said in a statement on Saturday.
The latest bloodshed was the second major bout of violence this month. A series of clashes two weeks ago between protesters and security forces left 157 people dead and over 6,000 wounded.
More than 2,000 people were injured nationwide in Friday's protests, according to medical sources and the Iraqi High Commission on Human Rights (IHCHR)."This is not a protest, this is a revolution," said one protester who declined to give his name.