The visiting side thought they opened the scoring in the first half through Jørgen Strand Larsen but it was disallowed after a VAR review adjudged Las Palmas defender Mika Mármol was fouled in the buildup.
The defeat sees Benitez's team drop into the relegation zone after eight matches and he was furious with the VAR decision.
"How can we not lose in the end? If we score a legal goal and they take it away from you," Benitez said in his postmatch interview.
"In that play, my player is ahead, he is in front, I'm watching it right now. I don't understand where the foul is. We will have to play something else if that is a foul.
"Anyone can see it, it makes no sense to call those things. It can't be, this is football. We're not talking about pingpong. We're continually rowing against the current."
The VAR officials failed to overturn the incorrect offside decision to disallow the goal leading the English referees' body PGMOL to issue a statement blaming "significant human error" in the Premier League game.
Liverpool released a statement on Monday saying that the mistake "undermined sporting integrity."
Forest and Brentford managers Steve Cooper and Thomas Frank were also highly critical of VAR following the 1-1 draw between their teams on Sunday.