The Blues have already seen two bids for the England international knocked back, with Red Devils boss David Moyes adamant that Rooney is not for sale.
Chelsea have refused to concede defeat, though, with it unclear what the 27-year-old has planned after a summer of uncertainty at Old Trafford.
Any suggestion that Rooney might be frozen out by Moyes would appear to have been put to bed, with a starting berth handed to him against Chelsea on Monday night.
Rooney's commitment to the United cause could not be faulted throughout a goalless draw, and Mourinho concedes it may now be difficult to lure him to Stamford Bridge.
He told Sky Sports: "First, we have to speak.
"I think this club must be a very special club because at any club in the world when a player wants to leave, they don't support him. When a player wants to leave, they give him a hard time, but they support him all the way.
"I think this a special club, with special fans, and if he makes that decision, we will be the first to respect that and to say it is over."
Pressed again on whether a fresh bid could be in the offing, Mourinho added: "It depends on this. It depends on his reaction, on his feelings.
"If now he doesn't want to leave, we are out. We need to know what is happening."