WASHINGTON -- The White House is calling for an end to violence in Iran as security forces there crack down on anti-government protesters.

White House press secretary Robert Gibbs said Wednesday that Obama administration leaders are following reports of the unrest and "hope greatly that violence will not spread."

In Tehran, Iranian security forces beat anti-government protesters with batons Wednesday on the sidelines of state-sanctioned rallies to mark the 30th anniversary of the U.S. Embassy takeover. The counter-demonstrations were the opposition's first major show of force on Tehran's streets in nearly two months.

Witnesses told The Associated Press that security forces swept through a gathering of hundreds of demonstrators, clubbing, kicking and slapping protesters.