"Obviously we're all deeply concerned with Nelson Mandela's health. He's a hero I think to all of us," Obama told reporters after his meeting with African leaders at the White House.
"I'm sure that I speak for the other leaders here. And we will be keeping him in our thoughts and prayers, and his entire family. He is as strong physically as he's been in character and in leadership over so many decades, and hopefully he will come out of this latest challenge," Obama said in response to a question.
"But we all recognise that he has given everything to his people, the people of South Africa, to the people of the continent, and he's ended up being an inspiration to all of us," he said.
"When you think of a single individual that embodies the kind of leadership qualities that I think we all aspire to, the first name that comes up is Nelson Mandela, and so we wish him all the very best," Obama said when asked about the health of the South African leader.
94-year old Mandela, the former South African President, was admitted to a hospital due to a recurrence of a lung infection, but was responding well.
"We appeal to the people of South Africa and the world to pray for our beloved 'Madiba' and his family and to keep them in their thoughts," South African President Jacob Zuma said in a statement. "We have full confidence in the medical team and know that they will do everything possible to ensure recovery."
The South African President said that Mandela was responding "positively" to treatment in the hospital.
Mandela served 27 years in jail under the white-minority apartheid regime. He was released in 1990. Four years later, he went on to become South Africa's first democratically elected president in 1994 under the banner of the African National Congress. He served as President from 1994 to 1999.