"I do not perform miracles," he said. "My team and I are not doing an experiment – an abominable term that is not in line with a serious medical view."
The seven-time world champion's condition hasn't been made public knowledge but a nurse told a local paper she could assure he was "conscious".
Schumacher's health has been kept in close secrecy ever since suffering a near-fatal brain injury when skiing with his son Mick in 2013.
The 50-year-old German driver spent three months in a medically induced coma after the accident and is currently under intensive care at his home in Switzerland.
In January, he was taken by helicopter to the family's home in Mallorca for his birthday.
In a post on Instagram for Schumacher's birthday, his family wrote: "Please understand if we are following Michael's wishes and keeping such a sensitive subject as health, as it has always been, in privacy."
They also confirmed that Schumacher was in "the very best hands".
Earlier this year, the head of Formula One Ross Brawn spoke publically about Corinna's decision to keep her husband's life in private.
"I am constantly in touch with Corinna, and I totally agree with their decision," he said.
"Michael has always been a very private person and that's been a guiding principle in his career, his life and his family always agreed with that choice.
"It's completely understandable that Corinna has wanted to maintain the same approach, even after the tragic event, and it's a decision we must all respect.
"I'm sure the millions of people who are still Michael fans will understand it, too."