"Fraudsters are sending poorly written text messages requesting that donations be made to charity, with the promise of a "winning cheque" for the donor once the endowment has been made," the Nelson Mandela Centre of Memory said in a statement.
The Centre warned people to ignore an SMS that purports to come from it.
"Please be advised that the Centre does not send unsolicited messages and that any such communication should be treated with suspicion," the Centre cautioned.
Meanwhile, President Jacob Zuma's office has said that Mandela, 95, remains in a critical but stable condition after being admitted on June 8 for recurring respiratory problem.