In injury-time, as Inter were chasing a goal to level the aggregate score, Stanisic pushed a local ball-boy after the pair battled for the ball.
The ball was initially in the possession of Inter coach Simone Inzaghi, who passed it onto the ball-boy before Stanisic intervened.
The shove sent the ball-boy backwards, falling off his stool. This led to Inter players confronting Stanisic before tempers were calmed.
Afterwards, Stanisic posted to social media: "Every team in the world, when they're leading, plays for time at the end.
"It was a bit stupid of me to push him.
"At that moment, I was just angry."
