"The provincial police commissioner [Lieutenant General Joel Mothiba] has informed me that people in Alexandra have been attacking buildings and assaulting others... the army is moving as we speak," Mokonyane said on the sidelines of the Independent Electoral Commission of SA (IEC) results centre.
ANC spokesperson Keith Khoza said the party was informed that the Economic Freedom Fighters (EFF) had been bussing in people into Alexandra to fuel the protests.
"A certain political party, which took part in this elections, is bringing people into the township, we do not condone violence and destruction of property," he said.
The protesters demanded the release of those arrested during a protest on Thursday, he said.
EFF Gauteng leader Dali Mpofu denied that his party brought in protesters into Alexandra.
"Members of the EFF, the DA and the IFP were all involved in yesterday's hostage situation over allegations of vote rigging, the EFF sent out lawyers to deal with the situation. We do not condone violence... and of course they would single out the EFF out of all parties involved," Mpofu said.
The IEC spokesperson Kate Bapela said the commission had heard about the protest, but had not received a complaint regarding the voting process in Alexandra.
Rubber bullet, stun grenades
Gauteng police said rubber bullets and stun grenades were fired on Friday afternoon to disperse protesting residents in Alexandra.
"Approximately 300 to 400 people gathered and burned tyres outside the court in Alexandra, protesting about the suspects arrested for public violence last night," spokesperson Neville Malila said in a statement.
He said police instructed the group to disperse, but they refused and barricaded streets.
"Police had to use stun grenades and rubber bullets to disperse the crowd, 44 people were arrested for public violence," Malila said.
"More police and metro police were deployed in the area to contain the situation."
Malila said later in the afternoon that the situation had abated and that the township was quiet but tense.
There was still debris and rocks in the streets, but the roads were now open, he said. No injuries were reported.
Earlier, Malila said a room in a community centre in the township that was used by the IEC was burned by residents on Thursday night.
There were people inside the centre at the time of the fire, but no injuries were reported.
Thirty-one people were arrested for Thursday night's fire.
Malila said the motive was unknown.
Both groups would appear in the Alexandra Magistrate's Court on Monday.