The Mac maker said it has stopped taking orders for the current iMac models and had hoped to have the new iMac available by the time the supply of current iMacs dries up.
"We planned to have our next-generation iMac ready by the time the inventory of current iMacs runs out in the next few weeks, but our planning was obviously less than perfect," Apple said in a statement
The company said the new model will be announced and made available in September. "We apologise for any inconvenience to our customers," Apple said.
Apple debuted the current generation of flat-panel iMacs in January 2002.
An Apple representative said the issue would not affect earnings for the third quarter, which ended Wednesday, but declined to comment on the effect for the current quarter, which runs from July through September.
