"It was embarrassing to be honest," Flintoff said ahead of his team's crucial Champions Trophy match against Australia here on Saturday.
"It was 10 seconds of madness. I think the series was hinged on the final over, but it is not something I am going to do again. I got a bit of stick in the dressing-room," said the England captain.
Flintoff did not please the purists when he celebrated his team's five-run victory over India at Mumbai in February 2002 by taking off his shirt. The win also helped England square the one-day series 3-3.
He played an important role in the series-levelling victory, scoring 40 runs and taking three wickets. He himself bowled the tight last over which denied India victory in a tense match.
India skipper Sourav Ganguly repeated the act when he took off his shirt at the Lord's balcony to celebrate his team's victory over England in the NatWest Trophy final the same year.
England and Australia need to win Saturday's game to keep alive hopes of making it to the semi-finals after losing their first match in the four-team Group A.
Australia lost to the West Indies and England to India. The top two teams advance to the semi-finals.