Marco Silva criticised the officials after Everton were beaten courtesy of Pierre-Emerick Aubameyang's offside goal at Arsenal.
His side had the better of the first 50 minutes of the game. But a quick-fire double from Alexandre Lacazette and Aubameyang before the hour ended up downing the visitors.
Arsenal counter-attacked up the pitch before the striker received the ball in an offside position from a flick-on and then scored. Assistant referee Harry Lennard failed to raise his flag.
And Silva was not happy with the decision.