Opposition candidates boycotted the vote, saying the constitution limited presidents to two terms in office.
Prosecutors said in April that 102 people were still being held over the violence, suggesting roughly 20 people remain in custody.
Opposition leaders Laurent Gbagbo and Henri Konan Bedie, both former presidents, had requested the prisoners release.
Gbagbo had asked for more than 100 people to be freed, including some who were involved in another bout of election-related violence during 2010 and 2011.
He argued that the detainees were political prisoners.