Violence broke out after a man in swimming trunks approached a woman sunbathing on grass outside a private leisure centre and reportedly touched her inappropriately.
The trouble erupted next to David Lloyd Leisure Centre in Speke when the suspect went over to the woman, enjoying last Friday's hot weather, and "touched her sexually."
He also whispered something into her ear, potentially lewd.
The incident sparked immediate anger from onlookers who challenged the man and a fight broke out between the suspect and another man.
The suspect escaped, at about 4pm, from the scene, at Speke Aerodrome.
The wanted man was wearing swimming trunks at the time.
He is white with a tan, of medium build, 5ft 9ins tall, with a bald or shaved head.
The woman was left "shaken" and "traumatised" and police today stated their wish to put the man "before the courts."
Detective Inspector Amy Smith, of Merseyside Police, said: “The victim was understandably left shaken and distressed by this incident, and we’re determined to track down the man responsible and put him before the courts.
"If you were at the leisure centre last Friday, saw what happened and have yet to come forward, please do so.
“Thankfully other people at the location intervened to prevent further escalation, but this will still have been a traumatic experience, and we’re supporting the victim at this time.
“We’re reviewing any CCTV footage and if you were parked at the location and may have captured such a person making off on dashcam, please check as identifying his vehicle could also be key to this investigation.”
Pass any information with reference 20000453387 via police's social media desk via Twitter @MerPolCC or Facebook ‘Merseyside Police Contact Centre’.
You can also contact the independent charity Crimestoppers anonymously, on 0800 555 111 or via their online form at: https://crimestoppers-uk.org/give-information/give-information.