The 32-year-old - substituted on for the final half-hour of the contest at Camp Nou - put his side back in the lead with 10 minutes of the contest remaining, but received his marching orders just two minutes later in controversial circumstances.
After outwitting Barcelona defender Gerard Pique and firing the ball into the back of the net, Ronaldo celebrated by taking his shirt off - an offence that resulted in him being issued with a standard yellow card.
Moments later he looked to be set for his second of the evening when he fell in the box under pressure from Samuel Umtiti, but referee Ricardo De Burgos Bengoetxea adjudged him to have dived and issued a second yellow.
Incensed by the decision, Ronaldo pushed Bengoetxea in the back before walking off the pitch.
According to Marca, the referee made reference to the incident in his post-match report, writing: "Once the red card was shown, the player pushed me slightly in a sign of disagreement."
Article 96 of the Spanish football rulebook states that any push of an official can result in a ban of between four to 12 matches.
Madrid went on to win the contest 3-1.