Agnelli did not single out individuals for the 2-0 reverse.
"We won't unload the blame on anyone," Agnelli said. "The group is united.
"The players must translate the club's objectives on the pitch. And after three excellent performances in terms of intensity and application there is a strong regret for the defeat to Lecce.
"After the game the players didn't need to have a shower. The fans and I are very disappointed with the result and the performance. The same team that beat Inter was on the pitch and there was no apparent reason for us to get the game wrong.
"We have to improve and also understand that we must give the maximum every time. The other directors, the technical staff and I represent a cohesive group, which has presented the ambitious objectives of the club.
"We have started down a long road. Next season there will be the second part of the job and if in a year's time we find ourselves in a similar situation we will have a problem.
"But for now we will keep going with serenity and we don't worry ourselves with comparisons to the past: I am not looking at last year at all. I am looking at today and tomorrow."