The broader public should have the democratic right to be irreverent about leaders, especially those who "display hypocrisy", cartoonist Jonathan Shapiro said on Friday afternoon.
"My latest cartoon is meant to be scathing but humorous," he said in an email, issued by his office, to Sapa.
"It's also serious commentary about a seriously flawed, hypocritical leader."
He was responding to criticism of his cartoon which was published in the Mail & Guardian on Friday.
The government has called for the urgent removal of the latest Zapiro cartoon, which features an erect penis with a showerhead and legs with an accompanying limerick about President Jacob Zuma.
The signature of artist Brett Murray is at the bottom corner of the mirror and the name of the Goodman Gallery also appears.
The illustration is under the heading "The Spear to be raised at Social Cohesion Summit".
The Spear is a painting, now defaced, by artist Brett Murray, which featured a depiction of Zuma with his genitals exposed.
In response to the painting the ANC launched a court application to have it removed from the Goodman Gallery and arranged a protest march to register its anger.
"I didn't put 'The Spear' back on the agenda. I responded to reports that it would be discussed at the Social Cohesion Summit," said Shapiro.
"The ANC asks why I didn't come to the summit: I wasn't invited. If I had gone there, I'd have said dissident views are vital in a democracy and are a force for change."
He said the Spear matter was not resolved properly.
"The ANC bullied the Goodman Gallery and the City Press into compromising. Freedom of expression suffered a blow," said Shapiro.
He expressed scepticism about the summit because it was an attempt to "encourage conformity rather than real diversity".
"Dissident views are essential for real change. Irreverence toward leaders who take themselves too seriously is a vital part of democracy."
"If ANC spokespeople feel the cartoon should be ignored then they are free to ignore it."
Earlier, government spokesperson Jimmy Manyi called on Shapiro and the newspaper to withdraw the cartoon saying it was a "defamatory attack" on Zuma's character and violated his rights to dignity as enshrined in the Constitution.
"It is disappointing that the Mail & Guardian published such a demeaning cartoon, especially following the recent debate about another offensive artwork," he said.
"While the Constitution and the government of South Africa promote freedom of expression, artists should ensure that they do not infringe on the rights of others, and that they build cohesion, dignity, and respect rather than undermine these imperatives."
The cartoon was condemned by the ruling party, which Zuma heads, its Women's League (ANCWL), and the National Union of Metalworkers of SA (Numsa).
"The Zapiro cartoons rely on their shock value to make an impact, but calling the president of this great nation a 'dick' is unacceptable..." ANC Womens League spokeswoman Troy Martens said.
The ANC said it was "taken aback" by it.
"We find it unacceptable and shocking that after the harsh experiences that South Africa, the President, and his family experienced [a] few weeks ago, that Zapiro and the Mail and Guardian will find it appropriate to continue with the insults and hurt to the President, his family, and the broader ANC constituency," said the ANC.
Numsa said the cartoon was "littered with venomous and deep personal hatred" of Zuma.
"As Numsa we can come to no other conclusion but to accept that some white progressives of yesteryear have become racist and colonialist in their outlook since the advent of our new democratic dispensation."
The ANC and Numsa have demanded an apology.