The Logo of social media app TikTok (also known as Douyin) is displayed on a smartphone on December 14, 2018 in Berlin, Germany.

Alongside high school dance videos and pranks, extremist propaganda has been lurking on TikTok.

TikTok has removed nearly two dozen accounts responsible for posting ISIS propaganda videos, The Wall Street Journal first reported. The videos reportedly presented armed ISIS militants, corpses and women proclaiming to be "jihadist and proud."

The posts come on the heels of the U.S. troop withdrawal from Syria, a time when the so-called Islamic State may look to bolster its strength in the region.

Extremist content is the latest challenge facing TikTok, which made headlines last week after lawmakers and competitors accused the app, which is owned by Beijing-based Bytedance, of censoring content on behalf of the Chinese government. The app has exploded in popularity across the U.S. over the past few months, particularly among teens.

"Content promoting terrorist organizations has absolutely no place on TikTok," a TikTok spokesperson said in a statement to CNBC. "We permanently ban any such accounts and associated devices as soon as identified, and we continuously develop ever-stronger controls to proactively detect suspicious activity."

TikTok's rules explicitly prohibit criminal organizations from using the app, but the company says enforcement of such guidelines is a problem that all social media companies face. A TikTok spokesperson said none of the videos had more than double-digit views. Popular TikTok videos can rack up tens or hundreds of thousands of views.

"This is an industry-wide challenge complicated by bad actors who actively seek to circumvent protective measures, but we have a team dedicated to aggressively protecting against malicious behavior on TikTok," a TikTok spokesperson said.

The presence of extremist content on the app may land TikTok in more hot water in Washington, D.C., where some lawmakers are already calling for investigation of the company over censorship concerns. While TikTok moved quickly to ban the extremist accounts after they were flagged to the company, some accounts had already garnered more than 1,000 followers, according to The Wall Street Journal.