"We are actively investigating these reports and will provide information as quickly as we can. In the meantime we have pulled back the iOS 8.0.1 update," an Apple spokesperson said in a statement quoted by multiple media outlets.
The update, iOS 8.0.1, was supposed to fix software problems with the new operating system released last week.
Users complained that after they downloaded the update they were unable to make phone calls and had problems with a fingerprint sensor used to unlock their phones.
TechCrunch reported for now only iPhone 6 and iPhone 6 Plus users appear to be affected.
The update was meant to resolve issues, including problems with software for the service HealthKit, which lets users track and monitor health and fitness data.