Sources have told ESPN that Spurs are locked in talks with Real over a deal to bring the 31-year-old back to north London seven years after he moved to Spain in what was then a world record £85.3 million fee.
Speaking ahead of Tottenham's Europa League second qualifying round match with Lokomotiv Plovdiv on Thursday, Mourinho said: "Gareth Bale is a Real Madrid player, I don't comment on players from other clubs.
"I tried to sign him for Real Madrid which was not possible. There is no secret on that. I think even Gareth knows that."
Sources have told ESPN that Madrid are pushing for a permanent transfer with Bale having two years remaining on his contract but Spurs are seeking an initial season-long loan.
Bale's agent Jonathan Barnett told the BBC late Wednesday that talks are "slowly progressing," but added that "Gareth is closer to leaving Madrid than at any time in the last seven years.
"We are still negotiating. We shall see how it goes."
The two clubs are compromising over Bale's £600,000-a-week wage, according to ESPN sources, with Tottenham ready to pay around £250,000-a-week to sign the Wales international.
Reports in the UK claimed midfielder Dele Alli has been suggested as a possible makeweight in the deal to sign Bale amid rumours of a deterioration in his relationship with Mourinho given he was taken off at half-time in Tottenham's 1-0 Premier League defeat to Everton on Sunday.
However, Mourinho played down the significance of that decision, adding:. "The change at half-time was not the first time in my career, will not be the last time.
"When I do these kind of things, I always do for the team. I never do it against a player. In some cases, the option was proven right. In some other cases the options is proven wrong. In this case, it didn't work. The team in the second half was not better than in the first half but that is my job: to make decisions. There is no story, no case.
"Dele is a very polite guy, he is very calm. I think he is a bit introspective, when you think a lot about things. So I think the way he reacted was Dele. He was quiet, he was sad but in the end after the game he was just one of many. But again I repeat: He is a good boy. He is very, very polite and I never saw a strong reaction from him. He is a good boy, a really good boy."
Bale scored 56 goals in 203 appearances for Spurs between 2007 and 2013 after arriving from Southampton in a deal worth an initial £5m in May 2007.