Kubrat Pulev has been suspended by the California State Athletic Commission (CSAC) and faces legal action after abruptly kissing a reporter on the lips following a post-fight interview on Saturday.
The 37-year-old heavyweight contender, who has only one loss in 27 fights, grabbed Jennifer Ravalo's face and kissed her on the lips after knocking out Romania's Bogdan Dinu in the seventh round in Costa Mesa, California.
"We take this incident seriously," CSAC Deputy Director of Communications Veronica Harms said.
"Before he will be licensed to fight in California again, boxer Kubrat Pulev must appear in front of the commission and demonstrate that he will conform to this principle of respect."
Pulev claimed he was friends with Ms. Ravalo but she denied that as she appeared with her lawyer.
She said: "Mid-interview he grabbed my face and kissed me. I was immediately shocked and embarrassed, and didn't know how to respond.
"Next, I walked to the table to put my items in my backpack. He grabbed both of my buttocks and squeezed with both of his hands. Then he walked away without saying anything to me and laughed.
"It made me feel uncomfortable and frustrated that Kubrat Pulev would treat me in such an unprofessional manner. I did not encourage or consent to Mr Pulev grabbing my face, kissing me, or grabbing my backside.
"I was there at the event covering the boxing match as a professional member of the press. Kissing a woman on her lips without her consent and grabbing her is not acceptable."
Pulev, one of Bulgaria's most popular sportsmen, has refused to apologise for kissing Ravalo.
"The reporter, Jenny, is actually a friend of mine, and after the interview, I was so elated I gave her a kiss," Pulev said. "Later that night, she joined me and my other friends at a post-fight celebration."