The opinionated Paris Saint-Germain and Sweden striker said he feared for the former Tottenham man as the Bernabeu crowd can be unforgiving if victories and trophies aren't being delivered.
In an interview with BBC Radio 5 Live, to be broadcast on Wednesday night at 8.30pm, Ibrahimovic said: 'I think nobody is worth paying that amount of money for. What is crazy in this kind of situation is the media and the club - the club are desperate to buy big names.
'There is a lot of pressure on him. I know that Zidane played for Real Madrid and they [the fans] whistled against him. Zidane is one of the best players in history. 'I hope that Bale has a lot of patience.'
Ibrahimovic moved from Inter Milan to Barcelona in a deal worth £58m in 2009 yet returned to Italy just two years later. Despite going on to establish himself at PSG as one of the best players in the world, he includes himself in his belief that nobody is worth that kind of money.
Ibrahimovic also talks fondly about Jose Mourinho, his manager for a season at Inter.
'He dragged out of me things that no other coach has done before,' he said. 'When I was playing, I was feeling so determined and so confident under him.
'The way he makes you feel, when I came out I was so confident in my game, we won the competition and I won the top scorer.
'The way he was, the personality he had, it was all clicking. There was no question about arguing with him, everything was flowing in a positive way.
'I felt much better as a football player in my mind and also in the way I was playing.'
Weight of expectation: Ibrahimovic scored 29 goals for Barcelona in two seasons after a £58m move from Inter Milan