Bale was largely sidelined for Spurs under Mourinho since his return on loan last year, and Barnett has claimed that his client was subjected to "unfair treatment".
"Nothing has been discussed at the moment. He had a tough ride and I don't think that should have been necessary," Barnett told Sky Sports when asked about Bale's future.
"He came as one of the best players in the world. Sure, he had a few injuries and a few fitness problems but once they were over, all he needed was to be played in the right position and to be played constantly to get back into the rhythm.
"He has been given that opportunity [under Mason] and you can see how he plays. I think with Gareth, like a lot of players, he has to enjoy his life and then you do well."
Barnett was also asked if any other club could prise Bale away once the transfer window opens to which he replied: "They would have to have a lot of money and they would have to be one that he has an interest in playing for. That rules out a lot of clubs."
Bale has scored 14 times and provided three assists so far, and is set to return to Real Madrid once his loan spell ends. It was revealed earlier this week that Spurs have "first refusal" on whether to sign Bale, according to the Daily Mail, the north London side would be open to bringing him on for another season due to the potential costs of bringing in a like-for-like replacement.
When asked about Bale’s future after the 4-0 thrashing of Sheffield United, interim manager Ryan Mason said: "I think that is a conversation at the end of the season between Gareth, the club and his parent club. Our main focus and priority should be the next game."