SAN FRANCISCO — Teenagers are gaga for TikTok. That’s why Silicon Valley is so worried about it.

TikTok, which is run by a seven-year-old company in Beijing called ByteDance, allows people to create short, snappy videos and share them around the world. That simple concept has fueled its rise to quickly become one of the world’s largest social networks and to mount the most direct incursion yet by a Chinese company into Silicon Valley’s turf.

Now the American internet companies are pushing back. Through knockoffs, potential acquisitions and not-so-subtle references to Chinese censorship, TikTok’s competitors have been trying to protect their home turf from the service’s advancement. They haven’t had much luck so far.

Over the past 12 months, TikTok’s app has been downloaded more than 750 million times, compared with 715 million for Facebook, 450 million for Instagram, 300 million for YouTube and 275 million for Snapchat, according to the research firm Sensor Tower.

But TikTok’s American competitors could still get some help from their government. The Committee on Foreign Investment in the United States, a federal panel that reviews foreign acquisitions of American firms, is now reviewing ByteDance’s two-year-old acquisition of Musical.ly, the American company that became TikTok, The New York Times and Reuters reported on Friday. Members of Congress had asked for a review last month.