By ESPNSTAR.com staff
The defending La Liga champions are 13 points behind the Catalan side and were held to a draw by Espanyol on Sunday night.
Mourinho had declared that "it's practically impossible" when questioned if his side still could wrest their way back into title contention.
Perez chose to remind the Portuguese coach that such defeatism was against the ethos of the club on Tuesday.
"One of Madrid's sporting principles is to never give up, no matter how difficult the challenge. One should never give up, not in sport or in life," he said.
"We should not only channel Real Madrid's strength into sporting objectives. The power of sport, our passion for football and for basketball puts Real Madrid in a strategic position with the ability to try to make a more equitable and supportive world."
Meanwhile, club legend Alfredo Di Stefano called on the club to not be perturbed by their domestic form and do their best to try and win a tenth Champions League title.
"We have an excellent team and a great manager who is going to put the guys on the right track to win our 10th Champions League," Di Stefano told Spanish daily Marca.
"There are those who have a talent for connecting with people. Real Madrid have that talent in connecting with the Champions League, which is what we need most now.
"We have to accept that failure is a necessary part of success. That's why we have to learn detailed lessons from our Liga defeats.
"Everything is relative and you have to learn that sometimes you win and other times you lose."
Madrid will find out about their opponents in the Champions League round of 16 when the draw takes place on Thursday.