Benitez was left less than impressed by referee Phil Dowd - and claimed fourth official Stuart Attwell was "too young" after watching his side lose their opening Premier League fixture 2-1 at Tottenham.
Benitez said: "Everybody could see there was a penalty against Voronin. It was so clear, it is unbelievable.
"With this referee, I knew this (another penalty) was impossible."
Asked for his overall assessment of Dowd, Benitez went to his pocket and pulled out his glasses.
The Liverpool manager added: "We had a meeting the other day, and they said we cannot talk about the referee as a person or the decisions, but I think everybody today could see the situation."
Attwell became the youngest referee in the Premier League when he took charge of Blackburn's match against Hull in August 2008.
Discussing Attwell, the Liverpool manager said: "The fourth official is a young referee, and maybe he needs to calm down a bit.
"I do not know how old he is, but the fourth official is too young."