The cardinal, who is the head of the Vatican's doctrinal office, dismissed speculation that the pontiff would retire and said he was returning to his old self.
"The pope is doing very well, but high-flow oxygen dries everything out. He needs to relearn how to speak, but his overall physical condition is as it was before," Fernandez said at a presentation of a new book by Francis on poetry.
The 88-year-old pope has been hospitalized for five weeks suffering from double pneumonia, during which time the Vatican has released just one brief audio of him speaking, on March 6, when his voice was broken, breathless and hard to understand.
In its latest health update released on Friday, the Vatican said the pope's condition remained stable with "minor improvements in breathing and mobility".
There is still no official word on when he might return home to the Vatican and Fernandez said he did not know if he would be discharged in time for Easter, which falls on April 20.
"He could return, but the doctors want to be 100% sure because he believes that with the little time he has left, he wants to dedicate himself entirely to others, not to himself," Fernandez said.
Asked if he thought Francis might step down, the cardinal said: "I really don't think so, no."
Francis has experienced several bouts of ill health over the last two years and is prone to lung infections because he had pleurisy as a young adult and had part of one lung removed.
