"He's playing less and believes he still has a lot to give. He won't want to continue here like this."
Apparently Rooney has also entertained bids from the US Major League Soccer and rivals Everton, although his £230,000-a-week ($NZ400,000) basic wage is a huge obstacle.
Mourinho was typically dismissive of the reports.
"Of course, I can't guarantee," he said. "I cannot guarantee that I'm here next week, how can I guarantee that a player is here next season?
"What I can guarantee is that if, one day, Wayne leaves the club, it is not because I want him to leave. I would never push a legend of this club to another destiny.
"You have to ask him if he sees himself staying in the club for the rest of his career or sees himself moving. It is not a question for me, because I am happy to have him.
"I was very open with you in the answer. I don't want him to leave."
Rooney has 18 months left on his current contract, with the option of a 12-month extension, but he has missed the last two games with a "muscle injury" and did not travel with the team for their Europa League tie with AS Saint-Etienne of France.