Seemingly frustrated by the close attentions of Edimar, Ballon d'Or winner Ronaldo reacted petulantly by swinging his right boot at the Cordoba defender.
A straight red card followed, leaving Real to play the closing stages of Saturday's match with 10 men, although a late penalty from Gareth Bale - awarded following a foul that saw Cordoba's Federico Cartabia dismissed - ensured Carlo Ancelotti's men still claimed victory.
After the match, Ronaldo took to Twitter to express his remorse.
"I apologise to all and especially to Edimar for my reckless act in the game today," said the Portugal captain.
Ronaldo has scored 28 goals in 18 Liga appearances this term, but now faces a spell on the sidelines through suspension.
Should he receive a three-match ban, he will be unavailable for Real's derby meeting with Atletico Madrid on February 7.
Real coach Ancelotti underlined his frustration with his team's performance prior to the interval against Cordoba.
"I didn't like the first half, that's why I was unhappy," the Italian is quoted as saying by AS. "It wasn't easy to play the ball because the pitch was irregular.
"We got the three points to stay top of the league, [but] we got them with some difficulty.
"Cordoba were competing for every ball and playing well on the counter-attack. We suffered to win this match and I congratulate Cordoba, but we got the three points."
Real's latest acquisition Lucas Silva was not signed in time to be able to feature on Saturday, but Ancelotti is excited about the Brazilian midfielder's arrival.
"He's a very good, very young player," Ancelotti added. "He will help us because he has quality and intelligence in his game. He will be very useful."
