Cuellar was furious with the reporter after a video of him giving fans a serious look emerged, when he was actually showing concern at the time for one supporter who was having an epileptic attack.
"Everyone puts out information that comes out of the b***s and c**k. Do you think it's nice to play with the health of a person?" blasted Pichu.
"You post a video and do not note that a person is having an epileptic attack. Allow me the luxury of telling you, you're an idiot. And it's no insult, it is an adjective. It's what you do, give information:... you're an idiot.
"I'm here to defend myself against an accusation that is not true. Before an important game, I cared for a person who was having an epileptic attack."
Cuellar's outburst has split Spanish football, but former Real Madrid fullback Arbeloa gave the goalkeeper his full support.
He tweeted: "Great 'Pichu' Cuellar. Showed b***s, crack. More like you. You have all our respect and support. A big hug."