The midfielder was involved in a fight with two men, and a picture of the incident, apparently showing a shirtless Barton being held back by police and a woman, appeared on Twitter.
But Barton played down the incident and revealed he would not press charges.
“Not planning on pressing charges as its not that serious. The police have also got better things to do with their time,” he wrote on Twitter.
Ian Taylor, a spokesman for QPR, added: “Joey Barton was involved in an incident in Liverpool city centre in the early hours of Monday morning. Barton was on his way home from a night out with his girlfriend when two men sang offensive chants and then proceeded to hit the R’s midfielder. Police were immediately on the scene and arrested one man.”
Liverpool-born Barton has a long history of controversy on and off the pitch and has become well-known for his voicing his opinions about football and the world at large on Twitter.
Last month, Barton was given a 12-match ban by the Football Association (FA), after being sent off during QPR’s defeat at Manchester City on the final day of the Premier League season.