NEW : He says attackers attacked his father 's house repeatedly to stop him from participating . Iranian opposition leader does not attend after his security chief advises him to stay away . He denounces Israel in a university speech . Some protesters are carrying Iranian flags and banners supporting Palestinians in the annual elections .
NEW : Son says attackers targeted his father 's house repeatedly to stop him from participating . Iranian opposition leader does not attend after his security force advises him to stay away . Ahmadinejad denounces Israel in a university speech . Some protesters are carrying Iranian flags and banners supporting Palestinians in the annual event .