The referee deemed his failure to initially award a penalty as a clear and obvious error, while he also allowed enough time for Pierre-Emerick Aubameyang to convert the rebound from his missed spot kick despite being over the allocated added-on time.
Smith was left frustrated with both decisions, which ultimately proved pivotal as the Gunners posted a 3-1 victory in North London.
Speaking to Sky Sports, Smith said: "It is a lower contact tackle. Grey areas, does he touch the ball first or his leg first? I thought they were the ones we were not going to VAR for. I am even wondering why he is allowed to put the rebound in.
"My understanding was he is walking off the pitch if he does not go to VAR, they cant give me any clarity on that."
A third successive defeat for Villa has left them sitting in 13th position in the top-flight standings. body check tags ::