Barcelona forward Lamine Yamal, who is of Equatorial Guinean and Moroccan heritage, was among the players targeted with xenophobic and racist abuse during the game at the Bernabeu stadium in Madrid.
Barcelona beat arch rivals Real 4-0, with Yamal among the scorers.
Spain's National Police said in a post on social media platform X on Saturday: "Three (people were) arrested for uttering racist insults against two football players during the El Clasico match played last October."
"Those arrested made xenophobic statements that violated the dignity and moral integrity of both footballers."
The Spanish Supreme Sports Council and La Liga condemned the incidents.
--Reuters--