"The ANC's response to the T-shirts produced by Westville pupils as part of an art exhibition is excessive, hysterical, and not in line with our Constitution," DA provincial leader Sizwe Mchunu said.
"These learners have the right to express themselves in whatever way they want to. This right is enshrined in our Constitution as the right to freedom of expression," he said in a statement.
T-shirts bearing the faces of President Jacob Zuma, former president Nelson Mandela and ANC national executive committee member and former police commissioner Bheki Cele, with derogatory captions, were displayed at the Westville Village Market Mall in Durban on Tuesday.
The provincial ANC on Wednesday expressed shock at the T-shirts made by Westville Boys High pupils.
On Thursday, ANC MPL in the KwaZulu-Natal legislature Siboniso Duma reportedly moved a motion demanding that Education MEC Peggy Nkonyeni launch an investigation.
Duma told the legislature the T-shirts smacked of a "DA tendency of promoting white supremacy by demonising the ANC government".
He was quoted by The Witness newspaper as saying that the DA was "a cancer to the society whose sole mandate is to destroy our society by promoting white supremacy and neo-liberalism".
"Public schools must serve our interests not the opposition. An investigation by the MEC must be done," he said.
The T-shirts were removed as soon as a complaint was received.
According to school principal Trevor Hall they had been produced as part of the visual arts curriculum, part of which focused on social commentary.
One of the T-shirts labelled ANC leaders as "fakers since 1994".
Hall told The Witness earlier this week that "the three artworks in question were created by free-thinking learners as part of their art portfolio for examination".
He said the work was not intended to offend and apologised for any offence caused.
Mchunu denied that the DA had anything to do with the T-shirts and said the pupils should be able to express their opinions without fear of retribution.
"The DA does not necessarily endorse the message produced by the pupils at Westville Boys High, and we certainly had nothing to do with producing or encouraging the art as the ANC has suggested," said Mchunu.
Had the pupils expressed a negative opinion about the DA, the party would not have complained about it.
"The ANC seems to have developed a hyper-sensitivity about being criticised. It is frankly laughable that the ANC feels this threatened by the handiwork of a few teenagers," he said.