Napoli repeatedly requested halt of Inter match due to racist chanting from crowd
Koulibaly was sent off with ten minutes remaining in Wednesday's Serie A fixture in Milan after receiving a second yellow card for sarcastically applauding the referee after picking up an earlier booking for a foul on Matteo Politano.
However, Koulibaly's frustration on the pitch was intensified by a series of racist 'monkey' chants which could be heard from sections of home supporters throughout the match.
"We asked three times for the match to be suspended and there were three announcements, but the match continued," Ancelotti said to Sky after the match.
"The player was irritable, he wasn’t in the best state of mind. Usually he’s a very calm and professional player but there were these noises throughout the game.
"It looks like an excuse but the player was agitated and irritable. It’s not good, not for us, nor for Italian football.
"The solution exists. You have to stop the match. You just have to know when, after how many announcements. And if we don’t know, then next time we may have to stop play ourselves."
Inter would claim the three points when Argentinian forward Lautaro Martinez scored in stoppage time after 90 minutes had elapsed.
An intensely frustrating night for Napoli was compounded when Lorenzo Insigne was issued his marching orders four minutes into injury time after a confrontation with Inter's Keita Balde.