By ERIC ROULEAU -- LeMonde, Parts

TEHERAN," Iran, June 13 — Violence has been sweeping Iran increasingly in recent weeks, with kidnappings, murders and sabotage creating a climate akin to civil war.

Pitched battles were fought here yesterday between members of the People's Mujahedeen, Iran's largest leftist opposition group, and fundamentalist Moslem supporters of Ayatollah Ruhollah Khomeini, and further violence was feared as the leader of Friday prayers denounced the leftists as counterrevolutionaries.

"Down with the deviationists!" Khomeini supporters shouted yesterday as they tried to force their way into the stadium where the People's Mujahedeen and tie Leftist Moslem Movement were holding a rally.

Rioting began at 4 P.M., an hour before the scheduled meeting, as tens of thousands of militants in sympathy with the People's Mujahedeen were standing in line outside the stadium, which is near the occupied United States Embassy. Khomeini supporters from the Party of God, known as the Hezbollahi, approached calling for "Death to Massoud Rajavi!" the leftist leader. "There is only one party." they chanted, "the Party of God, and one chief, Ayatollah Khomeini."

Police Decline to Act

The demonstrators charged forward repeatedly, throwing bricks and stones, causing thousands among those attacked to lift their hands about their heads to protect themselves as policemen and Islamic revolutionary guards stood by.

However, the police and guards did protect the assailants against the leftists' security forces, which appeared to be 10 o 20 times more numerous than the attackers. The police tried to separate hose fighting with tear gas or by shooting in the air. [Other accounts said revolutionary guards fired into the crowds of leftists, and, according to Reuters, the Iranian Interior Ministry subsequently criticized them for their action. At least two were said to have been killed and I the unemployed and pushcart vendors of more than 300 wounded.]

Leftist leaders charged this week that Ayatollah Mohammed Beheshti, the leader of the fundamentalist Islamic Republican Party, the majority group in Parliament, was the behind-the-scenes director of the Hezbollahi assailants. It was said they were recruited from among wing faction of the Beheshti party.

During the attacks yesterday those standing in line outside the stadium did not falter even when the deafening gunshots increased.

After two hours about 150,000 people were gathered inside to listen to Mr. Rajavi. "What to do?" was the theme of his address, in which he said dozens of leftists had been killed recently.

A cry came from the crowed. "My brother was killed the day before yesterday!" a weeping young woman in Western dress screamed. A woman, her head covered by a black chador, shouted: "We have feared neither the Shah nor his jails! We will fear nothing and nobody!"

The crowd chanted in rhythm, "We will pursue the struggle."

"Yes," answered Mr. Rajavi. "The struggle will last until victory, whatever the number of our martyrs may be."

"What are we being attacked for?" the speaker went on. "We are good Moslems, and we are told that we live in an Islamic Republic. But we are being besieged by hooligans and terrorists. The Islamic Constitution guarantees all liberties in principle. But we are forbidden access to the newspapers, to the radio, to television and to Parliament."

He said also that ethnic groups were ostensibly granted equality under the law but that the demands of the Kurds and other minorities were being drowned in blood.”

As he spoke, fighting continued outside and his words were lost at times in a cacophony of explosions, machine-gun bursts and ambulance horns. Clouds of black smoke spread over the stadium, but the masses inside sat listening, immobile as though made of stone, and then answering Mr. Rajavi on cue by invoking God.

A Fight for 'Total Freedom'

"Do you hear?" Mr. Rajavi asked as he addressed himself to the Hezbollahi. "We are neither Communists nor pro-Soviet as you claim. We are fighting for the total freedom and independence of Iran. You are the reactionary Moslems who under the cover of accusations thrown at us try and serve the occidental imperialism. Have we not heard that you prefer the Shah's regime a thousand times more than a progressive republic, even though Moslem?"

Mr. Rajavi said the Government remained silent as "these gangs of hoodlums" attacked the people and he warned that if those in power did not put an end to the violence his organization would take it upon itself to do so.

"Freedom is not granted," he cried as the crowd rose shouting to its feet. "It is won. A gift of the Lord, it is as indispensable as oxygen."

The meeting ended, but the fighting around the stadium continued. Mr. Rajavi's troops counterattacked, but the Islamic guards turned them back. Shots were fired from nearby roofs and bodies lay on the sidewalks.

Mr. Rajavi, expecting a surge of violence, did not sleep at home last night. For some time he has been living a semi-clandestine life, staying away even from his organization's headquarters. He believes, as does President Abolhassan Bani-Sadr, with whom he has a cordial relationship, that the Beheshti party is determined to monopolize power.