The North West ANC was "embarrassed and shamed" on Thursday after the party's Potchefstroom mayor was replaced by a DA councillor.
Provincial African National Congress spokesperson Kenny Morolong regretted that ANC councillors helped pass a motion of no-confidence in the former mayor.
"The provincial working committee (PWC) condemns these actions, which are alien to our movement and an insult to our people, who have since 1994 consistently voted the ANC into power," he said in a statement.
"The removal of the comrade [Maphetle] Maphetle and his replacement with Prof [Annette] Combrinck has brought... embarrassment and shame to the ANC."
Tlokwe (Potchefstroom) municipal spokesperson Willie Maphosa said Maphetle was voted out on Wednesday night, and Combrinck was voted in immediately afterwards.
The transition between the two mayors was "going smoothly" and the new mayor would address staff on Friday, he said.
Morolong said the motion was not an ANC decision, because it was "unknown to the organisation".
"The PWC extensively discussed this matter and committed itself to the re-instatement of... Maphetle as the mayor of Tlokwe," he said.
"The PWC will hold an urgent meeting with all ANC councillors today to communicate its decisions and the next course of action."
Earlier on Thursday, the ANC Youth League said the ANC had to recall its councillors in Potchefstroom.
"The African National Congress Youth League wants to emphatically voice its disappointment and displeasure at the conduct of councillors of the ANC in Tlokwe municipality," it said in a statement.
"It is expected that the national leadership of the ANC must act decisively and recall all those ANC councillors [who voted for the motion]," it said.
The North West Democratic Alliance said an ANC-driven motion of no-confidence in Maphetle was accepted, with 37 votes in favour and 13 against.
Combrinck became the first DA mayor in the province after defeating ANC candidate Lucky Tsagae by 20 votes to 19.
The national DA said its North West branch supported the motion because of allegations of corruption levelled at Maphetle.
Spokesperson Mmusi Maimane said the DA's "victory" showed how divisions in the ruling party were tearing it apart.
"The ANC in Tlokwe was so divided that it could not agree on a mayoral preference," Maimane said.
"For as long as the ANC in Tlokwe remains divided, the DA mayor will do everything possible to deliver the best services to the people of Tlokwe and display the DA difference in government."
The North West DA said the vote was indicative of the instability and infighting in the North West province.
The party's Tlokwe caucus leader Chris Landsberg said not all councillors had participated in the vote for the new mayor.
"A faction of the ANC left the chambers after the motion of no confidence was passed," he said.
The Freedom Front Plus said two of its councillors played a decisive role in the DA's victory.
"This is a telling example that shows that voters who support the Freedom Front Plus can make a difference in council decisions," provincial leader Pieter Groenewald said.
"It is also a good example that shows that different opposition parties have a right to exist, but can band together to oppose the ANC."
Several ANC members tabled a notice of a motion of no confidence in Combrinck shortly after she won the vote.
The national ANC said it would lodge a formal complaint with the Independent Broadcasting Complaints Commission after it was allegedly reported that executive member Jackson Mthembu attended the council meeting where Maphetle was ousted.