NEW : Electoral commission postpones voting in two states . The president tells protesters to avoid violence . Comment: Protesters in the mostly Muslim north charge the vote is rigged after Jonathan 's election .
NEW : Electoral commission postpones voting in two states . The president tells protesters to avoid violence . `` There are ... no grievances that our laws and courts can not address , '' he says . Protesters in the mostly Muslim north charge the vote is rigged after Jonathan 's election .