The clubs must agree a new date by Monday.
Manager Ernesto Valverde had said the Barcelona were against switching the game to Madrid as they play away to Slavia Prague in the Champions League on 23 October, three days before El Clasico had been scheduled.
Hundreds of thousands of people waving pro-independence flags and chanting “freedom for political prisoners” took part in marches across Catalonia on Friday
At least 96 people have been hurt across the region.
Catalonia is a semi-autonomous region in north-east Spain and in a referendum on 1 October 2017, declared illegal by Spain’s Constitutional Court, about 90% of Catalan votes cast backed independence. Turnout was 43%.
The nine separatist leaders were convicted of sedition over their role in the referendum and handed jail sentences of between nine and 13 years by Spain’s Supreme Court.