The apparently botched update came after a rash of complaints posted on social media about the reportedly fragile body on some of the large-screen iPhones which went on sale last week.
Apple released a tweak to its iOS 8 operating system, called iOS 8.0.1, but then pulled the software after complaints that the update disabled cellular service and Apple's touch-identification system.
Apple did not respond to an AFP query. But in a statement to the news website TechCrunch, Apple said: "We have received reports of an issue with the iOS 8.0.1 update. 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."
On the MacRumors forum of Apple users, one iPhone buyer noted that, after carrying the handset in a front pocket for 18 hours, "I saw the reflection of the window in the iPhones slightly distorted."
The user posted a picture of the bent iPhone, and dozens posted similar complaints on Twitter.
Apple said Monday it sold more than 10 million of the new smartphones in the first three days since launching in a handful of countries, setting a new record for opening weekend sales.
The new iPhones were launched Friday in the United States, Britain, Australia, Canada, France, Germany, Hong Kong, Japan, Puerto Rico and Singapore.
They will be available in more than 20 additional countries on September 26, and 115 countries by the end of the year.