He admitted: "I went into the Dáil bar but I wasn't drinking excessively. There was nothing pre-meditated, it was stupid, it was disrespectful."
Mr Barry was given a verbal warning in a call from FG general secretary Tom Curran.
The Cork East Deputy apologised for his behaviour and is said to be extremely embarrassed by the incident.
However, it has also emerged that there was backtracking within Fine Gael on its response to the controversy.
Ms Collins is understood to have been annoyed by the description of the incident by party officials as "horseplay".
A subsequent statement by the press office clarified the party's view and was more trenchant in its condemnation.
A number of female Fine Gael politicians are understood to have approached Ms Collins and asked if she wanted any further action taken – but she declined.
A colleague said: "She is embarrassed and just wants it to go away."
Video of the incident went viral on the internet after it was broadcast live on television, overshadowing the overnight Dail debate.
And it again raised questions about the male-dominated culture of the Dail – where only 25 out of 166 TDs are women.