The pan-African bloc called for action 10 months ago to curb the flow of weapons to insurgents that have been battling the U.N.-backed government for four years.
AU Peace and Security Commissioner Ramtane Lamamra said some African countries felt the United Nations was guilty of double standards over the pace at which it took decisions.
"Some of our member states drew on the fact that between the request made by the Arab League to impose a no-fly zone on Libya ... and the adoption only five days passed," Lamamra told reporters following a meeting between U.N. Security Council members and the AU in the Ethiopian capital, Addis Ababa.
"In the case of Somalia, 10 months have elapsed without a significant decision. These are the realities of today's international relations," he said.
"The official reaction is that those requests are still being considered," Lamamra added. He did not say which African states had voiced concern.
Somalia has been without an effective central government since the overthrow of dictator Mohamed Siad Barre in 1991. First clan warlord and now al Shabaab Islamist insurgents ensured the government controls little territory outside parts of the capital Mogadishu.
Washington says the militants are al Qaeda's proxy in the Horn of Africa nation, whose chronic instability has allowed piracy to flourish off its coast.
The AU has also been pushing the United Nations to send its own blue helmets to Somalia or "rehat" the existing African peacekeeping force, known as AMISOM, as a U.N. force.
The Security Council, which has already deployed large forces in Congo, Sudan and Ivory Coast is wary of sending troops into Somalia after the failure of a peacekeeping mission there in the 1990s.
AMISOM launched a new military push against al Shabaab on May 12, seizing several strategic positions.