When it comes to Europe’s lengthy investigations into Google, Margrethe Vestager, the region’s competition chief, is hoping that the third time’s a charm.

Ms. Vestager announced on Thursday a new round of antitrust charges against the company — the third set since early 2015 — claiming that some of the company’s advertising products had restricted consumer choice. The efforts are part of her continuing push to rein in Google’s activities in the European Union, where the Silicon Valley company has captured roughly 90 percent of the region’s online search market.

“Google’s conduct, based on our evidence, is harmful to consumers,” Ms. Vestager told reporters in Brussels on Thursday. “Google’s magnificent innovations don’t give it the right to deny competitors the chance to innovate.”

The announcement represents a setback for Google, which vigorously denied any wrongdoing in two previous European antitrust charges linked to Android, its popular mobile operating system, and some of its dominant online search services. It also comes at a difficult time for Europe’s competition authorities, which have been unable to land a knockout punch against Google’s perceived abusive activities in the region, despite investigations that date back to 2010.