The UN Security Council has voted unanimously to impose an immediate arms embargo on Ivory Coast, following the recent outbreak of violence there.
There were anti-French protests when AU leaders met in Abuja
Under the resolution, drafted by France, the ban will last 13 months.
The country's warring sides now have a month to revive a shaky peace process or face more sanctions.
Ivorian President Laurent Gbagbo accuses France - the former colonial power - of favouring the rebels in the divided West African country.
Meanwhile, the last emergency flight carrying foreign nationals from Ivory Coast has arrived in Paris, bringing to an end six days of evacuations overseen by the French military.
More than 4,500 foreigners have been evacuated during the past week.
One of the leaders of the former rebels - now known as the New Forces - who control the north of the country has welcomed the sanctions.
The leader said an arms embargo should have been imposed after the peace accord was signed in January 2003.
Ivory Coast's ambassador to the UN told the BBC his country had not had the chance to defend itself in front of the UN Security Council.
The ambassador said the embargo would favour the New Forces, arguing that they have always been able to obtain arms by illegal means, the BBC's James Copnall in Ivory Coast reports.
Civil war in Ivory Coast reignited 10 days ago, when the Ivorian armed forces broke a ceasefire by launching air attacks on the rebels.
Monday's vote at the 15-nation Security Council came after African leaders urged it to put the embargo in place without delay in a bid to try to defuse growing tensions in Ivory Coast - the world's top cocoa producer.
The resolution condemns the Ivorian air strikes and reiterates its full support for action carried out by the United Nations and French peacekeepers.
In a month's time, further sanctions will be considered, including travel restrictions or financial sanctions against individuals guilty of human rights abuses.
The resolution also expresses deep concern about the humanitarian situation in Ivory Coast and the use of the media to broadcast hate messages against foreigners.
Juan Mendez, who is a special adviser to Secretary General Kofi Annan, said he was "particularly distressed by reports of hate speech and the ensuing actions of armed militant groups".
War of words
Relations between Ivory Coast and France plummeted after nine French peacekeepers died in a government bombing raid, and France retaliated by destroying the small Ivorian air force.
29 Sept: Parliament fails to meet deadline for political reforms
15 Oct: Rebels ignore deadline for disarmament
28 Oct: Rebels withdraw from unity government
4 Nov: Government aircraft begin air strikes on rebel-held territory
6 Nov: Air strike kills nine French soldiers; France destroys Ivorian planes
7 Nov: Gbagbo supporters demonstrate against the French in Abidjan; UN condemns Ivorian attacks
8,9 Nov: Anti-French rioting
10 Nov: French begin evacuating civilians
14 Nov: African Union backs UN sanctions on both sides
The two nations have continued to exchange angry words.
President Gbagbo said the presence of French peacekeeping troops in Ivory Coast reminded him of the Soviet invasion of Czechoslovakia in 1968.
French Defence Minister Michele Alliot-Marie said President Gbagbo must stop anti-white propaganda and violence against foreign nationals.
He was responding to comments by French President Jacques Chirac, who said French troops would not allow what he described as "anarchy or a fascist regime" to develop in Ivory Coast.
He said France was "fulfilling its responsibilities" in Ivory Coast, backed by the UN and "all African countries".
France has 4,000 troops in Ivory Coast, backing a 6,000-strong UN force separating the north from the government-controlled south.