Luiz has established himself as a key player in the Chelsea Champions League-chasing side which secured a 1-0 Barclays Premier League win at Old Trafford on Sunday, but has been criticised for his role in the dismissal of his Brazil team-mate Rafael.
After being kicked by Rafael, Luiz was seen on the ground and smiling - his defence was that his smile was as a result of supporters' taunts over his likeness to The Simpsons character Sideshow Bob, who also has a mop of curly brown hair.
Luiz will not face any action from the Football Association over the incident.
Asked if he was aware who Sideshow Bob is, Benitez said: "I'm aware David Luiz is one of the best players in the Premier League, by miles - miles away from a lot of players. He's one of the best, without doubt.
"If we're talking about that, we're not talking about Chelsea beating United, doing much better in three games - two in Old Trafford.
"We did really well. The substitution of Fernando (Torres) was an offensive player on the pitch. Mind games. Nobody was talking about mind games after the game. Then we start talking about this.
"I don't agree. David Luiz was laughing because the fans were abusing him. After was the red card (for Rafael). It was very clear, the timing.
"If we continue talking about this, instead of trying to eradicate the bad tackles that you can see every week, I think we're giving importance to something that is not as important.
"I don't like this situation, but we are talking about one of the best players in the Premier League."