A man who allegedly punched former prime minister Kevin Rudd's godson during an argument about same-sex marriage has been charged with assault.

Police alleged the 48-year-old Murarrie man punched Sean, 19, at a bus stop in Bulimba on Monday.

Sean has said he doesn't want the incident to incite more violence. ( Bulimba 4 Marriage Equality )

The older man has also been charged with public nuisance offences and is due to face the Brisbane Magistrates Court next month.

The alleged assault occurred on the same day rainbow flags were ripped down from a roundabout on the same street.

Mr Rudd tweeted a photo of his godson with a gash to his head, saying he had been punched for standing up for marriage equality.

"So many warnings to [Malcolm] Turnbull about what the postal vote cld unleash," Mr Rudd tweeted at the time.

"Now my godson Sean has been punched standing up for #MarriageEquality."

The postal vote has been criticised for exposing children to hatred, with Labor senator Penny Wong labelling it as a damaging and expensive stunt to avoid having Parliament make a decision.

The Australian Bureau of Statistics began sending out same-sex marriage surveys on Tuesday, with the result due in November.