BRUSSELS—A new European privacy law took effect Friday, causing several major U.S. news websites to suspend access across the region as privacy activists filed complaints and data-protection regulators prepared to brandish their new enforcement powers.

Tronc Inc., publisher of the Los Angeles Times, New York Daily News and other U.S. newspapers, was among those that blocked readers in the European Union from accessing sites, as they scrambled to comply with the sweeping regulation.

“We are engaged on the issue and committed to looking at options that support our full range of digital offerings to the EU market,” Tronc said in notices it displayed when users attempted to access its news sites from the EU on Friday morning. A spokeswoman didn’t elaborate when asked for details.

Some U.S. regional newspapers owned by Lee Enterprises Inc. were also blocking access in the EU on Friday. Bookmarking app Instapaper, owned by Pinterest. Inc., said it was “temporarily unavailable” while the services makes changes “in light of” GDPR.

A spokesman for Lee Enterprises said that European traffic to its sites “is de minimis, and we believe blocking that traffic is in the best interest of our local media clients.”