Iran’s supreme leader, Ayatollah Ali Khamenei, angrily warned opposition leaders Friday to stay off the streets and denied opposition claims that last week’s disputed election was rigged, praising the ballot as an “epic moment that became a historic moment.”In a stern and lengthy sermon at Friday prayers in Tehran, he also called directly for an end to the protests that have brought hundreds of thousands of protesters onto the streets to back demands for a new election.“Street challenge is not acceptable,” he said. “This is challenging democracy after the elections.”His remarks seemed to reinforce the divide between Iran’s rulers and supporters of the main opposition candidate, Mir Hussein Moussavi, who have accused the authorities of rigging the vote.