Zuma, after months of pressure to do something about Julius Malema, said his party's leaders should "think before they speak, as their utterances have wider implications for the country."
Zuma said he spoke to Malema earlier in the week about his verbal abuse of a BBC journalist, his defiance of ANC policy on Zimbabwe and his performance of a song from the anti-apartheid era that could be deemed hate speech.
The telephone discussion apparently took place Thursday, soon after Malema expelled the journalist from an ANC Youth League news conference. The next day, Malema defended his own behavior and called on the journalist to apologize for interrupting him.
"The manner in which a BBC journalist was treated at an ANC Youth League press conference is regrettable and unacceptable, regardless of any alleged provocation on his part," Zuma said Saturday.
Zuma did not suspend or expel Malema from the party or from his position. The Youth League is known for getting voters to the polls, and local elections are coming.
Zuma did promise an investigation into whether Malema and other party leaders were defying ANC discipline, but would not say what sanctions they might face.
Malema traveled to Zimbabwe earlier this month and returned expressing praise for Zimbabwean President Robert Mugabe, who was forced into a power-sharing arrangement with his main opponents after a series of inconclusive elections marred by violence blamed on Mugabe's supporters.
Zuma, who is the chief mediator in talks aimed at getting Zimbabwe's leaders to resolve their differences and prepare for new elections, said Saturday that South Africa had to be neutral.
"We cannot and will not side with any one of the parties to the exclusion of others," Zuma said.
Malema also has revived an anti-apartheid era song that refers to killing white farmers. Opposition parties and civil rights groups have accused him of spreading hate speech, and a court has ordered the song banned. The ANC has appealed the ban, but asked its members to show restraint and respect the courts.
Citing the song, white supremacists have blamed Malema for the death of Eugene Terreblanche, who was killed April 3 in what police have described as a wage dispute with two black farmworkers.
"We do recognize that we have a responsibility to act in a way that reduces the potential for tension, and encourages unity," Zuma said Saturday.
* AP
