South African President Jacob Zuma has warned against "a resurgence of racism" in the country where "racists have become more emboldened".

"We have sadly not yet succeeded in building the non-racial society that we envisaged," Zuma said at the Chris Hani Wreath Laying Ceremony and handover of the Chris Hani heritage site in Boksburg, Gauteng province, on Monday.

The late Hani, South African Communist Party (SACP) General Secretary, was assassinated at his Boksburg home on April 10, 1993. His death almost derailed the reconciliation talks that led to the end of apartheid in 1994.

Zuma lauded Hani as a real fighter against racism, who lost his life at the hands of hard-core racists, Xinhua news agency reported.

The President linked last week's massive protests to racism, saying it demonstrated that "racism is real and exists in our country".

Thousands of South Africans marched in parts of the country to press their demand for the resignation of Zuma last Friday.

Although SACP leaders shared the same stage with Zuma in memory of Hani, the SACP said it has not changed its plea for Zuma to resign.

Zuma has come under mounting pressure after he reshuffled the cabinet on March 31, sacking or replacing 10 ministers and 10 deputy ministers, notably Finance Minister Pravin Gordhan.

Zuma said many placards and posters carried by the protesters "displayed beliefs that we thought had been buried in 1994".

Some posters depicted black people as baboons, Zuma said, adding that "it is clear that some of our white compatriots regard black people as being lesser human beings or sub-human".

"The racist onslaught has become more direct and is no longer hidden as was the case in the early years of our constitutional democratic order," said Zuma.

"We cannot allow and assist racists to take our country backwards."

At a legislative level, the South African government has published the Prevention and Combating of Hate Crimes and Hate Speech Bill, according to Zuma.

Once it becomes law, the law will criminalise several forms of discrimination including on the basis of race, gender, sexual orientation, religion and nationality.