Tennis star Naomi Osaka was fined $15,000 for not talking to the media after her straight set victory at the French Open on Sunday, Roland Garros announced in a statement.

On Wednesday, citing mental health reasons, the four-time major champion posted on social media that she will not participate in any press conferences during the French Open, hoping that any fine money she incurs will go toward a mental health charity.

"I've often felt that people have no regard for athletes mental health and this rings very true whenever I see a press conference or partake in one," Osaka wrote.

"We're often sat there and asked questions that we've been asked multiple times before or asked questions that bring doubt into our minds and I'm just not going to subject myself to people that doubt me."

Roland Garros said it asked Osaka "to reconsider her position and tried unsuccessfully to speak with her to check on her well-being, understand the specifics of her issue and what might be done to address it on site."

"Following the lack of engagement by Naomi Osaka, the Australian Open, Roland-Garros, Wimbledon and the US Open jointly wrote to her to check on her well-being and offer support, underline their commitment to all athletes' well-being and suggest dialog on the issue," the statement reads. "She was also reminded of her obligations, the consequences of not meeting them and that rules should equally apply to all players."

Organizers say that repeated violations could lead to tougher sanctions including default from the tournament.

Osaka had otherwise enjoyed a perfect start to her French Open campaign, beating Romania's Patricia Maria Tig in straight sets -- 6-4 7-6 (7-4) -- on Sunday. The 23-year-old has never been past the third round at the clay court major in Paris but looked powerful in her first round match.

Although her footwork occasionally let her down, the world No. 2 remained calm and composed on a surface that hasn't always been her best. "I would say it's a work in progress. Hopefully the more I play, the better it will get," Osaka said after her win.

She will next face Ana Bogdan of Romania.

text by Ben Church and Wayne Sterling