CONMEBOL president Alejandro Dominguez called for fans to behave in Madrid after the Copa Libertadores final second leg was rearranged.
Boca Juniors and River Plate will meet at the Santiago Bernabeu on December 9 to complete a tie which is locked at 2-2.
The second leg, which was due to be played at River's El Monumental, was postponed after the Boca bus was attacked on its way to the stadium.
The match will be played in front of fans from both Boca and River in a match that is designated as River's home match.