"Every production process produces its own factory faults, so that's what they are," he told reporters in Johannesburg.
"Some of them are well-known factory faults, old factory faults, who are joining this campaign."
Former ANC and SA Communist Party member Ronnie Kasrils and former deputy health minister Nozizwe Madlala-Routledge started the "Sidikiwe! Vukani! Vote No" campaign - which called on South Africans to either vote for a minority party, or spoil their ballots.
The campaign was joined by other former SACP members Vishwas Satgar and Mazibuko Jara.
Nzimande said there was no principle in what the group was doing.
"If Ronnie Kasrils wanted to appear so principled why didn't he do this at the height of Aids denialism when he was a minister or deputy minister.
"If he was a principled person, he would have walked away at that time," he said.
Nzimande said the group was just looking for attention and the ANC would "defeat" the campaign.
"Their message is not going to sink with our people. In fact I am amazed at how lightly they take the issue of a vote... We are just going to teach them a lesson on the 7th [May]."
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