Mourinho, speaking on his arrival in Malaysia for the latest leg of the club's pre-season tour, stonewalled direct questions about Rooney following Chelsea's rejected bid for the unsettled striker.
United continue to insist they will not sell but Rooney has been angered by new boss David Moyes's suggestion he could be back-up to Robin van Persie.
Mourinho confirmed on Wednesday that Rooney was his only name left on his summer wishlist and appeared to have the forward in mind when he was asked in Kuala Lumpur about the importance of regular first-team football, ahead of Brazil 2014.
He said: "For a player to be selected for his country, normally he must be first choice at his club.
"Any player that wants to go to the World Cup, if they are a second choice in their club they are in trouble. They are in trouble."
Rooney was at United's training complex on Thursday for ongoing treatment on his hamstring injury.
But Mourinho said any deal to bring him to west London would not involve a part-exchange for David Luiz or Juan Mata, contrary to reports.
Asked about the possibility of selling either, he said: "No chance. No chance.
"I am not going to contact them based on news that is not true and that they know that it is not true, because I told them they are very important for me.
"I spoke with them during the summer, in my period of holiday and their period in the Confederations Cup. I told them that I will see them on the 28th (28 July)."
Mourinho was also asked to assess the merits of Chelsea against their rival Premier League clubs.
He insisted it was not possible for him to compare, but that his thoughts were with the Blues in the intervening period between his September 2007 departure and his return last month.
"If Chelsea can become a really special club for me, it's because Chelsea can be a special club for everybody," Mourinho said.
"I left the club in 2007. I went to two fantastic football countries like Italy and Spain, I went to two fantastic football clubs like Inter Milan and Real Madrid and I was always wishing to be back.
"This club is so special that I'm back and I hope to stay for a long time. That's the only thing I can say, to every other professional in the world. This is my own experience. I'm back and I'm so happy I'm back."
Mourinho's wife was influential in his decision to leave Madrid and return to west London and he again pointed to his happiness.
"The most important thing in football, either for players or for managers is the passion, the happiness and the feelings we have for a club," the Portuguese said.
"We all are professionals, but at the same time we all are in love with our job.
"If you can execute your mission, your job - either as a player or a manager - not just because you are paid for it, not just because it's your job, it's your work, but because you can do it with happiness and passion and feeling, that's the most important thing.
"The most important thing for me is the deep feeling I'm at a really special football club.
"Not many clubs are like that, where people remember you and the fans sing your name, not just at Stamford Bridge but all over the world, you can't have a better feeling."