Aberdeen manager Derek McInnes says Inverness CT midfielder Ross Draper “conned” referee Willie Collum.
The second Caley Thistle goal in a 3-1 win came from a Greg Tansey penalty given when Draper went down under a challenge from Ash Taylor.
“It’s clearly not a penalty. Their player has tried to con the referee and he’s conned him,” said McInnes.
“It’s a dive, there’s no contact there. We’re disappointed, it’s such a big decision.”
Aberdeen remain three points behind Premiership leaders Celtic as their 12-game unbeaten run was halted in the Highlands.
Adam Rooney shot the visitors ahead, only for a Taylor blunder to set up an Iain Vigurs leveller.
The controversial penalty came early in the second half, with Carl Tremarco adding a header for the hosts, who move up to sixth place in the table.
“Taylor doesn’t protest [the penalty] because he’s already been booked for something he shouldn’t have been booked for, that was a poor decision, and he makes sure he doesn’t get sent off,” added McInnes.
“I actually thought we had a penalty with Graeme Shinnie when he gets his leg taken from him and we didn’t get that, and we had one or two other things that I haven’t seen again.”
Taylor had an evening to forget since his clumsy touch set up Vigurs to score and he touched on the cross for Tremarco to finish.
“I thought Inverness played well in that first half but we’ve obviously made a poor decision,” McInnes told BBC Scotland. “Ash should probably do everything but what he did.
“After that big decisions have went against us, both in their box and in ours.
“We can play better but we were still in the game, it was evenly poised. There’s no criticism of my players tonight because they’ve been absolutely terrific. We just have to pick ourselves up and start another run, starting on Friday [away to Partick Thistle].
“Inverness played well. When you see how determined they were it’s a surprise they aren’t higher up the table.”
Caley Thistle manager John Hughes admitted his side got lucky with the penalty decision, but was delighted with the performance of his team.
“What pleased me was the character we showed after losing the first goal. For long parts of the game our football was very good,” said Hughes.
“There was definitely a bit of luck. I would have felt hard done by had it [the penalty] been against us. But there’s plenty of luck went against us this season, and it’s about time we carried a bit of luck.
“I still think there’s more to come. I still want more goals from [Miles] Storey, I want a wee bit more from [Andrea] Mutombo, you can see Jordan Roberts is going to be an influential player for us.”
The Highlanders now travel to champions Celtic on Saturday and Hughes called for a similar performance in Glasgow.
“It’s a whole different ball game when you’re playing the champions at Parkhead,” he said. “It’s all about character and belief. We’ve got nothing to lose and you never know we might just upset Celtic as well.”