The France striker has been booed by Real fans, having only netted twice for the European champions so far this season.
Benzema was also targeted by supporters during the 2013-14 campaign, but Ancelotti stressed that there is more to the former Lyon frontman's game than just goals.
"Benzema doesn't need to worry about the fact that Cristiano scored four goals [against Elche on Tuesday], that's something to celebrate, because it means we have great goalscoring quality," he said.
"Karim isn't under pressure to score goals, his job is to work to help the team play better and give us solutions in attack."
The Italian also staunchly defended Real goalkeeping coach Villiam Vecchi after he came in for criticism in the Spanish media.
He said: "It makes no sense. Vecchi is the best goalkeeping coach in the world. He has more experience than anyone. It's rubbish, crazy."
Free-scoring Real, who have scored 13 goals in their last two La Liga games, face Villarreal at El Madrigal on Saturday.
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