Police fired tear gas and beat back protesters after violence broke out the Abobo and Adjame districts.
It was the first big demonstration by opposition supporters since the start of the civil war last September.
It comes a day after pro-government supporters staged a huge rally in Abidjan in protest at a French-sponsored peace deal seeking to bring an end to the violence.
On Saturday, mediators from West African nations left Ivory Coast with little indication of whether they had made progress in pushing the accord.
Slum violence
The latest violence flared after a body was discovered on Sunday morning in Adjame.
PEACE DEAL
Demonstrators accused government agents of killing the man, believed to be a supporter of the opposition Rally of the Republicans Party (RDR).
They hurled stones at police and set fire to at least two buses, according to reports.
Angry youths rampaged through the slums, burning tyres and setting up barricades.
Police fired rounds into the air and lobbed tear gas to quell the crowds as a police helicopters hovered overhead, Associated Press (AP) news agency reported.
A number of people were arrested.
Ethnic divisions
The RDR is so far the only political group to have officially backed the French peace deal.
Those involved in Sunday's violence were mainly ethnic Dioula, a northern-based Muslim tribe which supports the RDR, AP said.
Southern Ivorians, who are predominantly Christian, have accused the northern Muslims of backing the rebels in the four-month conflict.
Opponents of the deal on Saturday staged the largest protest since the conflict began, with up to 100,000 people taking to the streets.
They support Ivorian President Laurent Gbagbo - who agreed to the accord last Saturday - but believe that the peace pact mediated in Paris is unacceptable because it gives cabinet positions to rebels who tried to overthrow the president in a coup.