"I don't need to explain what a binding contract is, but effectively the clubs cannot leave," Perez told newspaper AS.
"Some of them, due to pressure, have said they're leaving. But this project, or one very similar, will move forward and I hope very soon."The Real president added it was "not true" American investment bank JP Morgan - who had provided a 3.5bn euro (£2.8bn) grant to the founding members - had abandoned the ESL.
"They have taken some time for reflection, just like the 12 clubs. If we need to make changes we will but the Super League is the best project we've thought of," Perez said.
"What we have done is taken a few weeks to reflect in light of the fury of certain people who don't want to lose their privileges and have manipulated the project."
Perez said on Thursday - in the aftermath of Arsenal, Chelsea, Liverpool, Manchester City, Manchester United and Tottenham's withdrawing - that the ESL was still on "standby".
La Liga club Atletico Madrid and Italian sides AC Milan and Inter Milan have also formally pulled out, while Juventus chairman Andrea Agnelli admitted the project could no longer proceed.
The 12-team Super League was announced on Sunday to widespread condemnation and has since prompted large protests outside grounds in England.
https://www.bbc.com/sport/football/56873448
