"The Presidency has noted media reports about the condition of former president Mandela and would like to make a clarification," Xinhua quoted the Presidency as saying in a statement.
On Thursday, some South African media report said Mandela was in a permanent vegetative state and that a life support machine was keeping him alive.
"We confirm our earlier statement released this afternoon (Thursday) after President Jacob Zuma visited Madiba (Mandela) in hospital that Madiba remains in a critical but stable condition," the Presidency said. "The doctors deny that the former president is in a vegetative state," the statement added.
"Mandela remains under the care of a multi-disciplinary panel of South African medical experts," it said.
On Thursday, the 94-year-old former president spent his 26th day at the Pretoria hospital since he was admitted there June 8 with a recurring lung infection.
Earlier Thursday, Mandela's wife Graca Machel said the former president may at times be uncomfortable and feel pain, but he was fine. Graca was speaking at the launch of a new sports initiative at the Nelson Mandela Centre for Memory in Johannesburg.
President Zuma has called on all South Africans to volunteer 67 minutes of their time on International Nelson Mandela Day, which falls July 18, to help change their communities and South Africa for the better.
This year's event will take place under the theme of "Take action; inspire change; make every day a Mandela Day" with focus on food security, shelter and literacy.