South African security officers forcibly removed members of the ultra-left Economic Freedom Fighters (EFF) party from parliament on Tuesday when they tried to prevent an address by President Jacob Zuma.
The EFF argued that Zuma was not fit to address the house after recent court decisions against the president, and said they would repeat their disruptive actions until he resigned.
The EFF's actions in parliament pile pressure on Zuma's ruling African National Congress ahead of local government elections in August, where the party faces a tough challenge from rivals seeking to take advantage of his missteps.
Malema and several members of his party scuffled with the security officials, with some being dragged out of the chamber.
"We are going to put our lives in defence of this constitution. Zuma will never find peace in this parliament," Malema told reporters after he was ejected from the assembly.
"We cannot be led by a man who failed to uphold, defend and protect the constitution," he said. "Anyone who manhandles us must know we've got the same capacity. Nobody has got monopoly on violence."
Police said last month they were investigating Malema for inflammatory speech after the politician threatened to remove Zuma's government through the "barrel of a gun".
Zuma remained calm throughout the chaos before taking the podium to address the parliament. He urged parties to behave with decorum in the assembly and deal with national problems.
"This house needs to do something about itself ... I believe that there is a lot that we have to do in this country to fight poverty," Zuma said.
The ruling party said in a statement that it wanted the EFF to face charges for its "disgraceful actions" in the assembly.
In April, the scandal-plagued Zuma survived an impeachment vote in parliament launched by the opposition after the constitutional court ruled he had ignored an order to repay state funds spent on his private home.
Later that month, the High Court overturned a previous decision seven years ago dropping 783 corruption charges against Zuma when he was still the country's deputy president.