Arsenal fell out of the top four spots in the Premier League standings on Saturday after losing 3-1 to Liverpool at Anfield thanks to goals from Roberto Firmino, Sadio Mane and an added time strike from Georginio Wijnaldum.
Firmino's goal had opened the scoring for Jurgen Klopp's side in just the ninth minute, which left Arsenal with a mountain to climb before Mane made it 2-0 with five minutes of the first half to play.
Arsene Wenger's introduction of Alexis Sanchez for the second period sparked a mini revival for the visitors, with the Chile international setting up Danny Welbeck's 57th-minute goal but Wijnaldum's late effort went on to seal all three points for the hosts.
Bellerin admitted after the game that Arsenal were made to pay for their slow start to the clash, and said the Gunners must show a "better attitude" in the future if they want to improve their poor away record against the top six sides.
"We’re very frustrated with how the game went," the Spaniard told Arsenal's official website. "After the tough weeks we’ve had, the team should have gone onto the pitch, motivated and ready from the start.
"In the first half it didn’t feel like we were ready and then we went 2-0 down. We wanted to do everything. We got one goal back and had a chance to make it 2-2, but sometimes it’s too late. We just need to start the games better.
"We need to realise that it’s just not the way to go. We need to push harder, to start the games with a better attitude and just go for it because we showed that when we go for it and want something, we can do it.
"It doesn’t matter about the other team, when we have the ball and push hard, we can score goals. It’s up to us to start the games with that desire, that motivation, and then we can get good results."