Real manager Zinedine Zidane has said he cannot guarantee Bale, Cristiano Ronaldo and Karim Benzema will stay at the Bernabeu this summer.
That has prompted reports Manchester United could rekindle their long-standing interest in the 28-year-old.
"It's a ridiculous, stupid story," agent Jonathan Barnett told BBC Sport.
Bale was hampered by injury last season and lost his place to Isco, but previously flourished under Zidane and was rewarded with a place on the 30-man shortlist for the 2016 Ballon d'Or.
However, with Real linked with a 180m euros (£160m) move for 18-year-old Monaco forward Kylian Mbappe, there have been reports that they will look to move on one of Bale, Ronaldo or Benzema.
Asked about the trio on Thursday, Zidane said: "I want everyone who is here now to stay but anything can happen right up until 31 August."
United first tried to sign Bale before he joined Tottenham from Southampton in 2007 and reignited their interest before his move to Spain four years ago.
Instead, though, the Welshman joined Real from Tottenham for a then world record fee of £85m.
He extended his contract in October 2016, committing him to the Bernabeu club until 2022 and on improved terms reportedly worth £600,000 per week, £350,000 after tax.
Despite helping Real win three Champions League titles in four years - scoring in the 2014 final win over rivals Atletico Madrid - Bale's time in Spain has been mixed.
During his second season, he struggled with calf injuries, was jeered by some Real supporters and faced criticism from sections of the Spanish media as Carlo Ancelotti's side failed to win a trophy.
Speculation linking Gareth Bale with a move away from Real Madrid is "ridiculous" and "stupid", according to the Wales forward's agent.