Singing on the bus provoked a violent assault and chase that left the victims with stitches, a broken nose, bruising and a cut in June.
Police on Friday released footage of two suspects caught on CCTV.
Two men apparently took offence to three people, aged 27 to 30, singing on the night bus from central London to Crystal Palace on June 6 at 3.30am.
The men began punching two of the victims and gave chase when the victims fled the bus in different directions along Dulwich Road and Hurst Road in Herne Hill.
Another suspect joined the chase and the men continued the attack during which a mobile phone was stolen.
Two suspects are described as black men aged 20-24, who were about 6ft 2in and 5ft 5in.
The third suspect, not pictured in CCTV images released by police, is described as a black man aged 18.
Police are appealing for witnesses and people with information about the attack to come forward.
Anyone with information should contact investigating officer Detective Constable Jenny Courtney on 020-8721-3582.
Alternatively you can report information to Crimestoppers anonymously on 0800 555 111.
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