The Israel defender was speaking after the 4-2 Europa League defeat by AC Milan on Thursday night kept them bottom of Group H with one point – they were already out before they travelled to the San Siro – and with two wins in their last 11 in all competitions.
The Scottish champions raced into a two-goal lead from strikes by Tom Rogic and Odsonne Edouard but goals from Hakan Calhanoglu and Samuel Castillejo had the home side level before the break with further goals from Jens Petter Hauge and substitute Brahim Diaz.
Celtic turn their focus on Sunday's Premiership game against St Johnstone at Parkhead where they will try to cut into Rangers' 11-point lead over them at the top of the Premiership, albeit Neil Lennon's side have two games in hand.
Bitton said: "Obviously we are disappointed with the result but I felt we played good as a team against a top side.
"Again, we conceded four goals and it's not good enough at this level. It's not good enough at any level.
"But I think in general we showed some moments of how good we can be.
"We are still a strong team. We don't listen to anyone outside the team.
"We believe in our quality, we have a strong squad, we have belief in ourselves and we need to show it now."
Asked about keeping confidence high amid some poor results, Bitton said:
"We are professionals, this is our job. This is what we need to deal with.
"Every team in the history has this moment where they go on a bad run.
"It has happened to us now, but we believe in ourselves, we believe we can turn it around, we believe in our quality.
"We have enough quality in the squad to make it happen and it's in our hands.
"We need to play for each other, support each other and only by being together can we do it."