Accompanied by security agents, Clinton had a drink at the salsa bar and then danced with a posse of her female aides, relaxing after a day at the side of U.S. President Barack Obama at the roughly 30-nation summit, which excluded Cuba.
"She looked like she was having a great time," said a person who saw Clinton at the bar and spoke on condition of anonymity.
Pictures of the outing, which began late because Clinton was at an official dinner until past midnight, emerged on the Internet, including one that showed her dancing beneath a sign that read Havana.
A US State Department official, who also spoke on condition of anonymity, confirmed Clinton went dancing at the bar. Asked if she had fun, the official replied: "A lot."
The bar is about as close as Clinton is likely to come to Cuba, which remains under a US trade embargo more than 50 years after Fidel Castro seized power on the Caribbean island and ushered in an era of communist rule.
According to a local paper, Clinton and her party of 12 ordered a dozen beers, two glasses of whiskey and bottles of water.
