The woman told police last month that when she refused, he struck her in face with his penis.
The woman told TMZ that after the alleged incident, one of Foxx's friends told her she had to leave.
She claims she went to hospital after returning home to Los Angeles the following day after suffering a severe panic attack.
Foxx's attorney told DailyMail.com: "Jamie Foxx emphatically denies that this incident ever occurred."
She added that he will be filing a claim with the Las Vegas Police Department against the woman for filing a false police report against him.
"The first time Mr Foxx became aware of this woman's absurd claims about an incident that supposedly occurred sixteen years ago was when TMZ contacted his representatives today about this story," she added.
"The alleged incident was not reported to law enforcement in 2002, or at any other time in the last sixteen years until last Friday because the incident never happened."
The police department lists the case as an open investigation, however, the statute of limitations in Nevada is three years so has run out.
The woman said she was inspired by the #MeToo movement to file a police report.
She said she wanted a record of the alleged assault in case other accusers come forward.
