McComb, who lost on points to England's Luke McCormack in the Round of 16 in the 64kg category on Sunday, was fined A$756 ($580) after the incident outside 'Sin City' early on Tuesday morning, local media reported, citing police.
The Northern Ireland chef de mission Robert McVeigh said 25-year-old McComb had been detained by police and released after a short period but had not returned to the athletes' village or reported back to the team.
"It is something we cannot condone and we have to apologise to the good people of Gold Coast and it is very disappointing when something like this happens," McVeigh said in a video posted on the BBC website.
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"This is a serious blow to our reputation. We are held in high esteem within the Commonwealth and we've done so over many, many Games.
"And to have something like this take away our success so far and the success we're going to have is really, really disappointing.
"We will interview Sean McComb when he comes in and we will be meeting with the police to see what action needs to be taken as a result of this."
McVeigh added it was possible that the light-welterweight boxer could be sent home early from the Games.
($1 = A$1.2943)
(Editing by John O'Brien)
