"A small number of customers have reported lower than expected battery life on iOS 5 devices," Apple said in a released statement.
"We have found a few bugs that are affecting battery life and we will release a software update to address those in a few weeks."
Apple's new iOS 5 operating system was released last month for iPhones, iPads, and iPod touch devices.
Some iPhone users took to Twitter and other online venues to complain about batteries not lasting through a day.
Forums developed online as people tried to solve the problem by tinkering with settings such as location-sensing capabilities in handsets.
While Apple reportedly contacted some iPhone 4S owners to ask about battery concerns, the comment Wednesday was the first time the company publicly addressed the issue.
The iPhone 4S has been a hit for Apple. The Cupertino, California-based company sold more than four million of the smartphones in the three days after it hit the market on October 4.
Apple said Tuesday that the latest version of its hot-selling smartphone will go on sale in more countries in Asia, Europe and Central America this month.
Apple said the iPhone 4S will be available on November 11 in Albania, Armenia, Bulgaria, El Salvador, Greece, Guatemala, Hong Kong, Malta, Montenegro, New Zealand, Panama, Poland, Portugal, Romania and South Korea.
The iPhone 4S will be available for preorder on November 4 except in Albania, El Salvador, Guatemala, Malta, Montenegro and Panama, it said.
Apple said the iPhone 4S will be available in more than 70 countries by the end of the year.