The Old Lady's ultras, Curva Scirea, didn't attend their team's 2-1 win over Atalanta in protest against their string of poor results this season.
After Sunday's game, some of the ardent fans showed up to hurl eggs and insults on the players and their bus.
One of the ultras even slapped French center back Jonathan Zebina, who has been panned of late, on the back of the head.
Bettega admitted that Juventus are not anywhere near their best, but highlighted the circumstances that resulted in their unpleasant status.
"We all know that we are not having a great season and even this victory cannot hide the problems," he said.
"Now we want to try and get our fans back as well as our fitness and the injured players.
"We had many absentees against Atalanta, but it's not right to throw this into the mix and diminish the work done by those who played.
"Now we'll also have a way of working with more tranquility as we don't have any more midweek commitments."
Juventus lie sixth in the Serie A table with 48 points, having slumped to 11 defeats this term.
Juventus' ultras gathering