Totti infuriated Lazio officials after yesterday's derby defeat with his 'thumbs down' gesture.
"It was disappointing that the end of the game was marred by this behaviour," said Reja after a scuffle broke out.
"Totti could've avoided that gesture and that moment sparked the problems. It was not sporting behaviour.
"There were some pushes and insults, but nothing else happened in the players' tunnel.
"I think Totti should be banned for 10 games."