Real Madrid president Florentino Perez said on Tuesday that the European Super League was created "to save football."
Real are one of the 12 European clubs who have signed up to the breakaway league and intend to establish a new midweek competition.
Perez said the move had been made because young people are "no longer shown any interest in football" because of "a lot of poor quality games".
"Whenever there is change, there are always people who oppose it," he said.
The English 'big six' of Arsenal, Chelsea, Liverpool, Manchester City, Manchester United and Tottenham have agreed to join the new league.