Arsene Wenger claimed Raheem Sterling "dives well" after Manchester City benefited from a controversial penalty decision in their 3-1 win over Arsenal.
Gunners boss Wenger also felt the offside flag should have been raised in the build-up to the Premier League leaders' third goal at the Etihad Stadium.
The spot-kick, awarded after Sterling was adjudged to have been bundled over by Nacho Monreal, allowed Sergio Aguero to put City 2-0 ahead early in the second half.
Wenger told the BBC's Match of the Day: "I believe it was no penalty. It was a provoked penalty by Sterling. We know that he dives well – he does that very well.
"And the third goal was offside. I am very upset because at 2-1 we were in the game and looked like we could score. The third goal was the killer.
"It is unfortunate that the game finished the way it finished. I am disappointed. You can accept it if City win in a normal way, they are a good side, but the way it happened is unacceptable.
"It is the second time in two years. We conceded two goals offside last year and we concede a goal here offside again."
Opposite number Pep Guardiola rebuffed Wenger's complaints by referring to the Gunners' contentious win at Burnley last season.
Guardiola said on Sky Sports: "We won in the best way and we deserved by far. The chances we created and the few chances we conceded.
"They tell me it was offside and I don't like to win in that way but sometimes Arsenal win in Burnley, 0-1, 96th minute, with a hand, so sometimes it is like this."
City are now as short as 1/7 with Sky Bet to win the Premier League title.
Arsenal have been pushed out from 66/1 to 100/1 to finish top and go to 7/4 from 11/10 for a top-four finish.