"I appeal to the SPLM and the SPLA to remove Salva Kiir from the leadership of the country," Machar said on Thursday. "He is tearing it apart and it is the right of the people, using their vanguard, which is the SPLM party and the SPLA, to remove someone who wants to make himself a dictator and somebody who mismanages issues of the state."
Earlier this week Kiir announced that he had defeated an attempted coup, closing borders and imposing a dusk-to-dawn curfew until further notice.
Hundreds have been killed since then in battles between Dinka soldiers loyal to President Salva Kiir and Nuers supporting Machar.
But Machar told RFI that the president is creating ethnic divisions.
"It is my responsibility, as well as the responsibility of others, to unite our people, all the ethnic groups in South Sudan - there are 65 of them," he said. "There is no enmity between the Nuer and the Dinka ... It is just the leadership, we have got the wrong leadership, that wants to in our new state ethnic tension for no reason."
Machar's comments came as three Indian peacekeepers were killed in in Jonglei state when attackers stormed a UN base where civilians had taken refuge.
The UN says it lost contact with the base at Akobo and the fate of more than 30 ethnic-Dinka civilians sheltering there remains unknown.