Sagna refused to condemn his former Arsenal team-mate Nasri, who he did admit "speaks his mind", after the midfielder had been at the centre of media criticism before the alleged incident.
"This is a sensitive issue and I was not there but I know when something does not please Samir he speaks his mind," Sagna, who was part of the last World cup squad, told L'Equipe.
"He can have a violent reaction but you have to share your responsibilities. When someone attacks the press it will not go away.
"With the excitement of the game and everything that was written about him it was perhaps not the right time to respond. He should have kept his cool but it weighed on him.
"The Euros had not even started and the press had already criticised him. Everyone is human."