Ministers in Kenya also said they would provide the International Criminal Court with details of investigations into the violence before the tribunal is established, the BBC reported.
The ministers promised to refer the case to the ICC if they did not set up a tribunal, the BBC said.
The violence erupted after President Mwai Kibaki was declared the winner of the December 2007 election and opposition leader Raila Odinga claimed electoral fraud.
The violence ended after Kofi Annan, the chief mediator, brokered a power-sharing deal.
Luis Moreno Ocampo, the chief prosecutor for the ICC, said he was satisfied with the new agreement.
"They will do the case themselves or, if they don't do that, they will refer the case to me," he told the BBC.