The federation said, "This is not a situation where any anti-doping rule was violated, but we decided to send a strong message to Michael because he disappointed so many people, particularly the hundreds of thousands of USA Swimming member kids who look up to him as a role model and a hero."
"Michael has voluntarily accepted this reprimand and has committed to earn back our trust," the statement said.
The photo which appeared in a British tabloid newspaper 'News of the World' on Sunday, Feb 1 was reportedly taken at a Nov party at the University of South Carolina. Phelps has repeatedly apologised for the incident and said he may backtrack on his plans to compete at the London Olympics in 2012.
Meanwhile the International Olympic Committee said that the Olympian's apology was proof of his sincerity and the world swimming's governing body FINA is also backing the embattled swimmer.
Michael Phelps has won 14 Olympic gold medals so far, making him the most successful competitor since the modern Olympics began 113 years ago.
OneIndia News (With inputs from Agencies)