Madiba has been in hospital since the 8th of December and continues to respond to treatment.
President Zuma assured him of the love and support of all South Africans, young and old, and the whole world.
"We urge South Africans to continue praying for our beloved Madiba during this period. Our hearts are with the whole family and relatives," said President Zuma.
Former President Nelson Mandela continues to respond to treatment as he marks two weeks of being hospitalised, the Presidency said on Saturday afternoon.
Zuma "assured him of the love and support of all South Africans, young and old, and the whole world," said presidential spokesperson Mac Maharaj in a statement.
Mandela, who is 94-years-old, was diagnosed with a lung infection and also underwent gallstone surgery.
He was originally flown to hospital in Pretoria from his Eastern Cape home at Qunu.
According to Associated Press, on Thursday, President Zuma gave the first official acknowledgement that Mandela's condition has been grave.
"I've been informed that, at his age, doctors need to intervene in a very gradual and sensitive way in order to maximize the chances of a full recovery," Zuma said at the time.
"The medical team has our full confidence and he is receiving the best care possible."
Mandela has a history of lung problems having suffered from tuberculosis towards the end of the 27 years he spent in prison.
His current stay in hospital is his longest since he was freed over two decades ago. – Sapa.