Mancini marched onto the pitch after his side had fought back from 2-0 down in the Group D encounter, only to have a goal disallowed and see a penalty claim turned down in the closing moments.
UEFA have confirmed that the incident was not reported by either referee Peter Rasmussen or their match delegate at the Etihad Stadium.
When asked what he said to the referee, Mancini explained: "I said it was a goal. I didn't see the last situation with Mario that was a penalty. I said it was a goal.
"The referee and his staff were really poor tonight."
UEFA had previously handed Arsenal boss Arsene Wenger a one-match ban after calling referee Massimo Busacca 'embarrassing' after a defeat by Barcelona in 2011.