Officers said the alleged assault occurred early Friday morning in Milledgeville, about 85 miles southeast of Atlanta. Roethlisberger owns a home about 30 miles to the north on Oconee Lake.
Deputy Police Chief Richard Malone said Roethlisberger had been with three other people who were mingling with another group that included the alleged victim. Malone said the woman, a 20-year-old college student, and her party contacted a nearby police officer following the alleged assault.
"He's been identified as being at the scene and there are allegations naming him as the perpetrator," Malone said.
Several areas of the bar were considered a crime scene, Malone said, but he would not elaborate.
Roethlisberger and the alleged victim have been interviewed and the woman was taken to a hospital, where she was treated and released, Malone said.
Police said Roethlisberger and his attorney were cooperating with investigators. He was not in custody and has not been charged with a crime.
Separately, Roethlisberger has been sued by a woman who claims he raped her in 2008 at a Lake Tahoe hotel. The Steelers star denies those allegations and has asked for counter-damages.
Roethlisberger's agent, Ryan Tollner, said in a statement that they are skeptical of the motive of the alleged victim in Milledgeville because of the previous Lake Tahoe allegations against the player.
"Last night, Ben and his friends met a group of women and everyone mingled together throughout the evening," the statement said. "We have spoken to law enforcement. Based on information currently available, an allegation was made against Ben, which appeared to be dismissed after a preliminary investigation last night. Obviously, given the prior accusation against Ben, we are skeptical of motive, but we will continue to cooperate with everyone involved."
Steelers spokesman Dave Lockett said the team was gathering information and had no more comment.
Pittsburgh's first-round draft pick out of Miami of Ohio in 2004, Roethlisberger led the Steelers to Super Bowl victories at the end of the 2006 and 2008 seasons. But while he has been a huge success on the field, Roethlisberger has had his share of problems off it.
Besides the Lake Tahoe allegations, Roethlisberger broke his jaw and several other facial bones in 2006 when he got into a motorcycle crash while driving without a valid license.