Mongols bikie boss Toby Mitchell has been bailed after he was charged following an investigation into an alleged assault in Melbourne's inner-south earlier this month.

The alleged serious assault occurred outside a cafe on Domain Road in South Yarra on October 4.

It is not yet clear what sparked the alleged incident, which was witnessed by multiple people.

Detectives from the Echo Taskforce arrested Mitchell, 45, at his Southbank address this morning.

The Mongols' president was interviewed by police and charged this afternoon with affray, intentionally cause injury, common law assault and unlawful assault.

He must not associate with Mongols as part of his bail conditions.

Anyone with information is urged to contact Crime Stoppers on 1800 333 000.

Source: 9News