"These are very excellent doctors who are dealing with him," Zuma said in a joint press conference with US president Barack Obama.
"We hope that very soon he will be out of hospital," he added.
Zuma called Mandela the "founding president of our democracy who is much loved by our people and the world".
Obama, who is here on an official visit, plans to meet with Mandela's relatives privately, but does not intend to see the man he has called a "personal hero."
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Obama decided not to visit his hero in hospital to preserve the "peace and comfort" of the anti-apartheid legend.
"The triumph of Nelson Mandela and this nation speaks to something very deep in the human spirit," Obama said after talks with Zuma.
Obama had said yesterday he did not need a photo-op with Mandela, whom he meet briefly in 2005.
Well-wishers are continuing to gather outside the hospital where Mandela, regarded the founding father of South Africa's multiracial democracy, was admitted 21 days ago.
Mandela had a long history of lung problems, dating back to the time when he was a political prisoner on Robben Island during apartheid. While in jail he contracted tuberculosis.
Mandela is revered for leading the fight against white minority rule in the African country and then preaching reconciliation despite being imprisoned for 27 years.
Mandela served as the country's first black president from 1994 to 1999.He left power after five years as president.
He retired from public life in 2004 and has not been seen in public since the football World Cup finals in in 2010.