The Royal Spanish Football Federation says it is not responsible for security during El Clasico and warned it could impose sporting sanctions if political demonstrations lead to trouble at next week's Camp Nou match.
Barcelona are due to host bitter rivals Real Madrid on December 18 in the fixture that was initially due to take place in October.
The original contest was postponed due to political tension that led to violent scenes in Catalonia after nine Catalan political leaders received long prison sentences for their roles in the region's 2017 referendum and subsequent unilateral declaration of independence.
A rally had been called for October 26 – the first date set for the Clasico – and it was decided to rearrange the match for security reasons.
But the Tsunami Democratic protest group – formed of Catalan independence activists – says it has called on its supporters to head to four meeting points near Camp Nou at 4pm local time on the day of the Clasico. Tsunami Democratic says more than 18,000 are due to join its protest.
📻⚽ ¿Se deber jugar el Clásico o se debe suspender definitivamente?— El Larguero (@ellarguero) December 10, 2019
The football federation (RFEF) has since made the decision to remind Barcelona the federation is not responsible for the organising of security, while also warning of sanctions if "the application of sports discipline is necessary".
A statement from the RFEF read: "In relation to the game on December 18 at the Camp Nou between Barcelona and Real Madrid, the RFEF states that, exactly as in all meetings of official competitions and being a public event, it does not hold responsibility in security matters.
"The RFEF will apply the regulations in force both before and during and after the game if there are situations of force majeure or circumstances in which the application of sports discipline is necessary.
"Similarly, as usual, the RFEF is in contact with the security forces to coordinate the arrival of the refereeing team at the Camp Nou facilities according to established protocols."