The Brazilian carried the ball into the box and messed up a chance, after which the Betis legend was seen on camera criticising the youngster's finishing.
"This is very bad," was the comment he made as he stood warming up on the sidelines, a comment captured by the cameras of Movistar.
"It was a comment that came out when it shouldn't have," he explained to Canal Sur Radio.
"It's not that he's a bad player, because he wouldn't be at Real Madrid if he was.
"I honestly felt so bad and I want to publicly apologise because he's 19 years of age, you know I'm not like that.
"He's a phenomenon and has a bright future.
"I didn't say it with any other intentions."