Yoon Chang-jung was accused of sexually assaulting a 21-year-old Korean-American at a hotel in Washington, D.C., on Tuesday while he was accompanying President Park Geun-hye on her first officials trip to the United States, Yonhap News Agency reported.
He returned to Seoul on Wednesday and has since been questioned by police about the incident.
"I apologize for causing concern to President Park and the people, and for causing harm to the accomplishments of the successful U.S. visit," Yoon said in a press briefing held in a Seoul restaurant. "But I didn't have any intention of sexual harassing her."
The victim told police in the United States that Yoon "grabbed her buttocks without her permission," a police report states.
However, Yoon, 56, said he patted her lower back and offered her words of encouragement.
"I think there was a misunderstanding between us because of cultural differences," Yoon said. "If I have hurt her, I ask for her understanding and offer an apology."
South Korea's ruling Saenuri Party criticized Yoon, saying he was making excuses and called for a thorough investigation into the incident.
"The press briefing in which [Yoon] made personal excuses and denied responsibility was very disappointing," party spokeswoman Min Hyun-joo said in a statement. "His briefing only brought more suspicions, rather than clearing up them."