LONDON — European Union regulators leveled their first charges Monday under the bloc’s new digital competition rulebook, accusing Apple of preventing app makers from pointing users to cheaper options outside its App Store.

The European Commission said that according to the preliminary findings of its investigation, the restrictions that the iPhone maker imposes on developers using its mobile App Store had breached the 27- nation bloc’s Digital Markets Act.

T he rulebook, also known as the DMA, is a sweeping set of regulations aimed at preventing tech “gatekeepers” from cornering digital markets under threat of heavy financial penalties. The commission opened an initial round of investigations after it took effect in March, including a separate ongoing probe into whether Apple is doing enough to allow iPhone users to easily change web browsers, and other cases involving Google and Meta.

Apple has been facing pressure on both sides of the Atlantic to tear down some of the competitive barriers around its lucrative iPhone franchise. The U.S. Justice Department filed a sweeping antitrust lawsuit against Apple this year, accusing it of illegally monopolizing the smartphone market and boxing out competitors, stifling innovation and keeping prices artificially high. App makers such as Spotify have complained for years about Apple’s requirement that subscriptions only be bought through iOS apps, allowing the company to take a commission of up to 30%.

Under the DMA’s provisions, app developers must be allowed to inform customers of cheaper purchasing options and direct them to those offers.