The announcement by Ahmed bin Heli, the 22-member group's deputy chief, follows a request by Gulf states to cancel the May 10-11 event because of political unrest across the region.
Iraq's Deputy Foreign Minister Labid Abawi said Baghdad had hoped the summit would be held on time but that the majority of League members wanted it postponed over tensions in the region. He said another meeting will be held May 15 to decide on a new date.
The summit was to discuss the unrest in the region and choose a new secretary-general to succeed Amr Moussa, whose term ends on May 15.
Iraqi Foreign Minister Hoshyar Zebari has said he is prepared to postpone but not cancel the summit.
Another League official said the summit will probably be held in September. He spoke on condition of anonymity because he was not authorized to speak to the media.
The summit, first scheduled for March, was initially delayed amid security concerns in Iraq and because it was unclear which Arab leaders could come while the region was in turmoil. Though disappointed, many Iraqis took that delay in stride.
The Arab League summit was considered by many Iraqi officials as an opportunity to show off the strides the country has made since the height of the US-led war, and they have spent millions of dollars refurbishing buildings and hotels in anticipation of the meeting.
