Like almost everybody who runs a big tech company these days, Alex Zhu, the head of the of-the-moment video app TikTok, is worried about an image problem.

To him — and to millions of TikTok’s users — the app is a haven for creativity, earnest self-expression and silly dance videos. In almost no time, TikTok has emerged as the refreshing weirdo upstart of the American social media landscape, reconfiguring the culture in its joyful, strange wake.

But to some people in the United States government, TikTok is a menace. And one big reason is the nationality of its owner, a seven-year-old Chinese social media company called ByteDance. The fear is that TikTok is exposing America’s youth to Communist Party indoctrination and smuggling their data to Beijing’s servers.

The desire to fix this perception gap is what brought Mr. Zhu last week to a WeWork in Manhattan, where a handful of his colleagues are based. Mr. Zhu, a trim 40-year-old who speaks fluent if lightly accented English, helped found Musical.ly, a Shanghai-based lip-syncing app that ByteDance acquired in 2017 and folded into TikTok.