Bournemouth led 2-0 at halftime after a Junior Kroupi brace, before Palace roared back in the second half, drawing level just before the 70-minute mark.
But the Cherries regained the lead with one minute left to play of the 90 through Ryan Christie.
That was not to be the deciding goal, though, as Palace were awarded a penalty deep into stoppage time, which Jean-Philippe Mateta converted to complete his hattrick.
Match report:
Iraola was left fuming at that decision, but felt the host’s equaliser had been coming.
“I suppose for the neutrals watching it must have been entertaining because there have happened a lot of things in the game,” Iraola told the Daily Echo, reacting to the game.
“I think we've been better in the first half, but they've been clearly better in the second half and you could feel that the draw was coming because they were pushing us a lot in that moment.
“But I'm not happy and not pleased because to receive the call of the penalty we received, I cannot be pleased in the 96th minute.
“It's very difficult to win in this stadium. They are a very good team. But to lose the two points the way we've lost it, I cannot be happy. I'm upset and I'm angry.”