Florentino Perez has called on Real Madrid fans to stop whistling players after admitting that Iker Casillas' exit from Real Madrid left a "bad impression."
Casillas spent 25 years at the club and made 725 official appearances for Los Blancos before departing for Porto in July with two years left on his contract.
The 34-year-old goalkeeper announced his departure from Madrid in a news conference without any representatives from the club, though he was later given a suitable farewell alongside all of the trophies he won during his Bernabeu career.
The Spain No. 1 came in for criticism from Madrid fans last season for some disappointing displays, while the Spanish giants tried and failed to sign David De Gea from Manchester United this summer.
Madrid fans have turned on a number of star players in the past including Zinedine Zidane, Karim Benzema and most recently Gareth Bale, but club president Perez says the criticism from the Bernabeu stands must end.
"Casillas' send-off didn't leave a good impression," Perez said in an interview with El Larguero. "People were saying that Casillas had been kicked out of the club. I called him that evening after that first farewell and said, 'Iker, this doesn't look good,' so he repeated it with all of the trophies he had won.
"But that's not talked about; they say that Casillas was kicked out. Casillas had gone through a rough time for two years. I have always defended him. He said that he felt isolated? No. I always supported him.
"The episode with Casillas has given us all something to reflect on. Whistling our players has got to stop. Those who whistle Casillas are whistling us, the club."
Bale has struggled to win over supporters and pundits in Spain despite scoring in both the Champions League and Copa del Rey final successes in 2014, but thanked Madrid fans for their support in August.
Madrid have been criticised by the Spanish press for their treatment of Casillas and also for De Gea's failed move.
Perez feels United showed a lack of experience in the failed De Gea deal, and is unsure of whether the 24-year-old will ever join Madrid.
The Blancos president defended himself by saying that he facilitated Casillas' departure, saying: "As a consequence of that situation, Casillas told us, 'Help me to join Porto.' It was a good solution and a good operation. All I did was help him."
On Madrid reportedly handing the keeper a big payoff, he added: "And to those who question why we are still paying him? Everything we have done is because he deserves it. He told us that he did not want anything special laid on. Casillas thinks very highly of De Gea and holds him in high regard."