In an Instagram video, Ronaldo said: “They want to promote [themselves] by [using] my name. It’s normal.”
Ronaldo’s lawyers say they will sue Germany’s Der Spiegel magazine, which originally reported the allegations.
The magazine wrote that Kathryn Mayorga had claimed Ronaldo, 33, sexually assaulted her in a hotel room in Las Vegas.
Ms Mayorga, 34, is reported to have filed a sexual assault report with Las Vegas police shortly after the alleged incident.
In 2010, she reportedly reached an out-of-court settlement with Ronaldo involving a $375,000 (£288,000) payment for agreeing never to go public with the allegations.
Her lawyers are now seeking to declare the non-disclosure agreement void.
In a statement, Ronaldo’s lawyer Christian Schertz said “the reporting in Spiegel is blatantly illegal”.
He added that he had been instructed to seek compensation for “moral damages” over “probably one of the most serious violations of personal rights in recent years”.
Ronaldo joined Italy’s Juventus from Real Madrid for £99.2m earlier this year.
The Portuguese international is regarded as one of the greatest players of all time.
H/T BBC Sports
