On Tuesday, for the second day running, hundreds of supporters of Laurent Gbagbo, the country's president, took to the streets of the commercial capital Abidjan and other cities to oppose a call by foreign mediators to end the mandate of the national parliament.
The anti-UN riots threw into confusion international efforts to reunite peacefully the world's top cocoa grower, which has been split since a 2002 civil war between a rebel-held north and a government-controlled south.
The protesters barricaded streets and besieged the UN mission headquarters in Abidjan, where some tried to batter down the wall, prompting UN troops to fire warning shots and tear gas. Demonstrators threw petrol bombs at the UN headquarters.
A UN military source said at least one demonstrator was believed to have been injured.
A convoy of UN vehicles was stoned and at Guiglo in the west of Ivory Coast, hundreds of pro-Gbagbo demonstrators entered a UN military base calling for the withdrawal of the international peacekeepers.
Annan, the UN secretary-general, condemned what he called "the orchestrated violence directed against the United Nations" in Abidjan, Daloa, San Pedro and Guiglo and other areas.
Stephane Dujarric, Annan's spokesman said, Annan was also critical of the inaction of some national authorities in the face of the attacks
Dujarric said: "The secretary-general demands an immediate end to these attacks, which contravene Ivorian law and seriously endanger the peace process as set out by the African Union and the UN Security Council."
The United Nations and international mediators are struggling to implement a long-delayed peace plan that requires a presidential election to be held by the end of October following a process of disarmament.
"The secretary-general demands an immediate end to these attacks"
Kofi Annan's spokesman
In a blow to the UN-backed efforts, Gbagbo's Ivorian Popular Front party (FPI) said it was pulling out of the peace process. It called for the withdrawal of more than 7000 UN troops and police and 4000 French soldiers who have together been maintaining a shaky peace in the country.
Demonstrators also protested outside a French military base in Abidjan.
Gbagbo met Pierre Schori, the UN mission chief to discuss the situation.