The Spanish keeper was hoping to be able to make his loan move to Napoli permanent, but Benitez insists the club can't afford to sign him.
“Pepe has two years left on his contract at Liverpool,” said the former Liverpool boss.
“He has to go back and he’ll stay there. We can’t afford Pepe’s wages.
“The Premier League is a very big league and, in Serie A, we don’t pay big wages like in England.
“He will have to fight for his position at Liverpool.”