In the opening minutes of the second-half, Marcus Tavernier appeared to be ankle clipped by Brentford fullback Michael Kayode inside the visitors' penalty area.
Speaking with the Daily Echo, Iraola fumed afterwards: “Big, big, massive penalty that I cannot accept that it hasn't been called.
“They've been checking for two minutes because the ball hasn't gone out. It has hit the post, I think.
“’We are checking, we are checking, we are checking’, you don't need to check a lot.
“It's three seconds, you see the situation. Kayode has lost his position, Tav is going to score an open goal. He just starts behind the calf.
“Somehow Tavernier finishes the play and hits the post, and probably that's the reason the ref doesn't give it live, but the VAR, you don't need three replays.
“I was convinced they were going to give it because they were checking, they were checking, they were checking.
“The game was on, was on, was on. Okay, they are checking, two, three minutes checking. Okay, but after they haven't done— for me it's so clear, so clear, but we haven't had the decision.”