The suspect has been dealt with by the South Wales police.
Former UK rugby captain Gareth Thomas, 44, appeared on Twitter over the weekend with cuts and scrapes to the face to say he was the victim of a hate crime because of his sexuality.
Thomas, who has been out publically since 2009 says he wanted to keep the social media message uplifting.
"Why I want to be positive because I want to say thank you to the police who were involved and were very helpful and allowed me to do restorative justice to the people who did," he says adding that he sought restorative justice to the people involved. "I thought they could learn more that way than any other way."
He adds that the people of Cardiff were very understanding and supportive, "because there are a lot of people out there who want to hurt us but unfortunately for them, there's a lot more who want to help us heal. This I hope is a positive message."
International Gay Rugby (IGR) released a statement today saying they stand shoulder to shoulder with Thomas and condemn the attacks which followed Wales’ 74 - 24 win over Tonga on Saturday.
“To us Gareth is a hero, one of the few brave enough in men’s rugby to stand up and be open about who he is, said IGR Chair Ben Owen said. "But it shouldn’t be that way, it shouldn’t take bravery to be who you are or to go out for a few pints to celebrate your team winning."
Owen continued to say that hate crimes have no place in 21st century Britain or in rugby and that the violent actions by homophobes are not representative of the sporting community as a whole.
"International Gay Rugby will continue to work at a grassroots level, with national unions and with World Rugby to make sure rugby remains a sport for all - a sport that says no the intolerance and bigotry that was seen in Cardiff on Saturday night."
South Wales police say the teenager was dealt with at the request of Thomas, and the suspect was very apologetic.
"Restorative justice is about putting victim needs at the centre of the criminal justice system," they said in a statement, "finding positive solutions to crime and encouraging young people to be accountable for the consequences of their actions."