The 29-year-old was one of six players fined for a breach of team discipline on Friday night following the six-wicket defeat to Group C rivals New Zealand.
He was suspended for Sunday's victory over Canada which leaves England needing another win over Kenya to qualify for the next Super Eight stage.
After leaving a nightclub close to the team's St Lucia hotel, Flintoff got into a pedalo on the water in the early hours and later needed to be rescued after falling off it, according to British media reports.
"There's no secret we had a few drinks on Friday. It's been documented in the press what happened afterwards with a little bit of poetic licence," a downbeat Flintoff told reporters at the hotel.
"There was water involved and a pedalo as well. But I don't want to go into detail. I don't think my life was in danger.
"It's something that I'm not proud of and something which shouldn't have happened. Being left out for these reasons is something I'm upset about and I never want to happen again."
Players Kissing: More revelations about Friday's antics appeared in British newspapers on Monday, with some witnesses saying the players were so drunk in the nightclub they were kissing each other.
James Anderson, Jon Lewis, Ian Bell, Paul Nixon and Liam Plunkett were the other players fined.
Flintoff, who has slimmed down considerably from his early cricket days, would not comment in detail about having the vice-captaincy taken away but was focused on Saturday's final group game with Kenya.
"I can't look at that in this moment of time. It was a horrible feeling (to be dropped). I enjoy playing for England and want to continue doing that," he said.
"Hopefully, I get picked on Saturday to play against Kenya. I've had things in my career before when I was younger that I had to come back from.
"I desperately want to perform. I feel I let the team down over the weekend. All I can do is apologise."
As he left the news conference, Flintoff was applauded by tourists and England fans in the hotel lobby. He signed autographs, shook hands and posed for photographs
Vaughany denies 'drink culture': Menawhile England captain Michael Vaughan insisted his side did not have a drink culture after Andrew Flintoff was dropped from the team which registered a 51-run World Cup win against Canada.
Former skipper Nasser Hussain, who led England from 1999 to 2003 when Vaughan took over as skipper, hinted at a drink problem within the England squad.
But Vaughan was adamant the recent excesses were a one-off.
"I don't see a drinking culture within this England team. I see a little bit of immaturity on Friday night and a little bit of a lack of common sense.
"It was a big mistake and a bad mistake but I don't see any drinking culture within the England cricket team.
"We knew we lost the big game against New Zealand, we knew we were playing Canada on Sunday. We know how hard it is to play two games in three days in this kind of heat and we just didn't use common sense."
He added any hurt he felt was nothing compared to that of England's fans.
"The supporters have been let down. They want to see the England cricket team focused on what is a massive tournament."
Vaughan said of Flintoff, who reportedly had to be rescued after capsizing a pedalo at 4am on Saturday morning: "He's angry with himself for what he did. He and I want him playing cricket for England.
"I wanted him out there entertaining the crowd today. The World Cup wants to see the best players and an unfortunate incident like this has taken one of the greats of the game out of the game.
In a statement, the 29-year-old Flintoff said: "I know that what I did on Friday night was completely wrong and I have to take full responsibility for it.
"There can be no excuses on my part. I know I shouldn't have done what I did and I have to accept the punishment.
"To my team-mates and the England supporters that I let down, all I can say is that I am extremely sorry and assure everyone that I will be giving 110 percent for England for the rest of this tournament."
Despite the controversy, Flintoff will be available for England's next group match, against Kenya, on Saturday.
"There's nothing that can repay what they did but hopefully a victory today, and us winning next Saturday and a decent run in the World Cup will be the only way we can say sorry to the supporters," Vaughan said.
Canada, a side with just one full-time professional, posted their best World Cup score of 228 for seven.
But Vaughan said any embarrassment England felt Sunday at being unable to bowl out the minnows, had to be set against the pre-match build-up.
"With what's happened over the last 48 hours, the victory was the most important thing.
"We put a lot of undue pressure on ourselves and today's game was about coming out, doing the basics pretty well, getting a victory and getting our World Cup back on the road.
"We are the first to admit that there's areas of the batting we need to improve, areas of fielding, and some of our bowling was a bit erratic at times. But the most important thing today was about winning."
Kenya, who play New Zealand on Tuesday, thrashed Canada by seven wickets in their first match and Vaughan warned the Africans would be no pushovers.
"It's going to be a hard game. We want to be in the World Cup for a few weeks yet. We have to make sure we unite as a team and work hard this week leading into that Kenya game."