The Argentine reacted angrily after being booed off by sections of the home support in Real Madrid's win on Monday, but his coach tried to play it down.
The Argentine winger was replaced with the scored deadlocked at 0-0 and sections of the Santiago Bernabeu vented their frustration with his display by booing him off the pitch - prompting an angry reaction.
Ancelotti claimed he did not see the incident at the time but insists the player made a simple mistake after a frustrating outing for the team and tried to play down the incident.
"I didn't see it. I took him off because I thought it was better to put two fresh players out," Ancelotti said after the match. "If he made the gesture, nothing happens. It's a mistake, but who doesn't make mistakes? If he responded with a gesture to the crowd then it's another mistake, but life goes on.
"He tried to play, just like everyone else did. Sometimes whistles are positive and afterwards the team improved."
Cristiano Ronaldo passed 400 career goals after scoring twice late on in the 3-0 victory and the Italian coach was thrilled to see him find the net after deploying him alongside Karim Benzema in a striker role.
"We changed for this match. I know Cristiano likes to play wider, but sometimes it's important to play him with Benzema. He scored two goals from an unusual position," Ancelotti added.
The Blancos boss also praised the efforts of youngsters Jese Rodriguez and Dani Carvajal - who both registered assists in the win - and made it clear the three points were crucial as Madrid look to keep pace at the top of La Liga.
"Jese can be one of our most important players even without starting the game," said Ancelotti. "When your opponents are tired it's important to have a fast player. Carvajal did great work with his two crosses which led to two goals. Occasionally we need to take risks, they defended deep and were compact.
"The game showed there were problems with our balance and we need to improve. I think it's important at this moment not to allow the gap to the leaders [Barcelona and Atletico Madrid] to increase. There are many games in January, and we need to keep winning. I'll field the strongest team possible on Thursday [against Osasuna]."