An Iranian leftist group holding a rally at a football stadium next to the U.S. Embassy here today was attacked by stone-throwing Islamic fundamentalist gangs in the worst violence in Tehran in two months. About 300 persons were reported injured, two by gunshots.

The stadium in which the leftists Islamic group, the Mujahedn, held its rally was to have been used as a helicopter landing point in America's aborted attempt in April to rescue the U.S. hostages.

Today, 30,000 Mujahedin showed up for a speech by their leader Massound Rajavi, only to meet a smaller group of fundamentalists, known as Hezbollahi (partisans of god), who tried to break up the rally.

The Hezbollahi, lower-class gangs recruited from the bazaars who wear their hair closely cropped, clashed in April with other leftists on the university campus.

Revolutionary Guards tried to separate the two groups today, firing tear gas and automatic rifles into the air. Most of those injured were hit by stones or cut in knife fights. Rajavi, in a two-hour speech, warned that his group would not be intimidated by attacks on them.

One Iranian woman said the rally attracted many people who do not support the Mujahedin but who wanted to show their opposition to the fundamentalists clergy who have taken a dominant position in running the country.