When Apple blocked the Beeper Mini app last month from giving Android users access to the tech giant’s messaging service, Beeper encouraged customers to use their Mac computers instead to connect and continue sending messages.

But in recent days, dozens of Beeper customers have reported that they no longer have access to Apple’s messaging service on their Android phones or their Mac computers. Several have called Apple’s customer support and been told that the company had revoked their Mac’s access to iMessage because of irregular activity. None had been warned that they would be losing the service.

For Beeper customers, many of whom prefer Android devices to iPhones but favor Mac computers over PCs, Apple’s move shows just how far the company will go to maintain control over its services. In these instances, Apple cut off one of the services that it provided with its computers because it had objected to the way its customers used it.

“Legally, they’re probably in the clear because of their terms of service, but it’s still kind of crappy,” said Matvei Vevitsis, who noticed this month that he could no longer send his mother iMessages through his 12-inch MacBook.

Apple declined to comment. After The New York Times contacted Apple, some Beeper customers began reporting that they had been unblocked in recent days.

The maneuver is the latest in a tit-for-tat between Apple and Beeper that has gotten the attention of antitrust regulators. Last year, the Justice Department met with Beeper’s leadership team about Apple’s actions, and the Federal Trade Commission said in a blog that it would scrutinize “dominant” players that “use privacy and security as a justification to disallow interoperability” between services.