Beijing prosecutors have filed a civil legal action against Tencent over claims its messaging-app WeChat's Youth Mode does not comply with laws protecting minors.
Youth Mode prevents younger users from accessing payments, playing certain games and finding nearby friends.
However, prosecutors have not specified exactly how the app is allegedly violating Chinese law.
Tencent said it would "investigate" the claim.
"We will earnestly inspect and check the functions of WeChat Youth Mode, accept user suggestions humbly and sincerely respond to civil public-interest litigation," the company posted on Weibo.
WeChat, known as Weixin in China, has about 1.26 billion monthly active users.
Last week, Chinese authorities called for minors to be better protected from online dangers, with a state-media article labelling games as "spiritual opium".
Tencent's share price fell by more than 10% shortly after the article was published.
And it swiftly announced stricter limits for younger players of its hugely popular game Honour of Kings.
Young players can now access the game for only an hour a day on weekdays.
Play time in China was previously capped at:
- 90 minutes on weekdays
- three hours on weekends and holidays
The mobile title has more than 100 million users worldwide.
In April, it was reported Chinese authorities were preparing a substantial fine for Tencent as part of its efforts to clamp down on internet giants.