The RFEF issued a statement on its website on Friday detailing the fine, in accordance with article 101.2 of its disciplinary code which describes objects being thrown on to the playing surface as "an infraction of a serious nature".
The match was halted in the 55th minute for 90 seconds as yellow inflatable balls were hurled on to the pitch as part of a protest against the jailing of Catalan separatist leaders.
The game, which was originally pencilled in for Oct. 26 but postponed for security reasons after mass demonstrations in Barcelona, took place amid a large pro-independence protest outside the Camp Nou which left 42 people injured.