BEIRUT — Ban Ki-moon, the UN’s secretary general, on Monday expressed disappointment with President Bashar Assad of Syria for rejecting the most important elements of an international road map to end the country’s civil war: a political handover and establishment of a transitional governing body.

Assad in a rare speech Sunday outlined his vision for ending the country’s conflict with a plan that would keep him in power. He also dismissed any chance of dialogue with the armed opposition and called on Syrians to fight what he called ‘‘murderous criminals.’’