The Welshman had a slow start to life on loan at his old club this term.
However, Bale has recently come to the fore, starting regularly in the Premier League and contributing vital goals and assists.
There is no option to buy in the loan agreement that took Bale to Spurs this term.
Speaking to reporters, Mourinho said: "In relation to that you should contact your colleagues in Madrid and they should ask (Zinedine) Zidane as he is a Real Madrid player.
"He is not a Tottenham player so Real Madrid have everything in their hands. They have a player with one year of contract and have the power in their hands.
"I just have a player on loan and I am trying to take the best out of the player for Tottenham Hotspur.
"We try to take care of the player we have on loan for us but also for the respect we have for the club who loans the player.
"If you want to ask anything about Gareth's future ask your colleagues in Madrid to ask Zidane."