Marcelino claimed Liverpool pushed the boundaries of the rules as Villarreal lost their Europa League semi-final tie, while suggesting the referee aided the English hosts.
Villarreal saw their 1-0 first-leg lead overturned by Liverpool, who triumphed 3-0 at Anfield on Thursday.
"It was tough against an opponent who played with huge amounts of intensity, maybe on the margins of the rules but the referee allowed it," Marcelino said.
"In the context of this game the referee was letting a lot go, so to then see a sending off against you, you make your own conclusions."
Marcelino did offer credit to the hosts, adding: "We've caught Liverpool in their best form of the season, there's not a lot more to say. They were superior.
"Liverpool played better than us but for all their superiority they didn't create too many chances."
