The Gunners held out thanks to the heroics of Aaron Ramsdale before going 1-0 down courtesy of Sadio Mane's header, with Diogo Jota, Mohamed Salah and Takumi Minamino adding further strikes in the second half.
Arsenal saw their 10-game unbeaten run in all competitions come to an abrupt end, with individual mistakes proving costly on the day, and Arteta has lamented such errors.
Speaking to reporters at his post-match press conference, Arteta said: "We competed really well in the first half - they had their moments, we had our moments.
"We were really compact and used the ball in the right way to create some situations. We had a goal disallowed and then we conceded a goal from a set-play. In the second half, when we had to build some momentum and start to grow [into] the match, we threw it away in the first 15 to 20 minutes.
"We gave every ball away in very dangerous areas. We had [them under] no pressure. They punished us, we lost control of the game and they had all the momentum."
Arsenal missed the chance to leapfrog Liverpool in the table and remain fifth with 20 points to their name from 12 matches.