Law enforcement investigators say at least $5 million has been funneled into the United States from sources in Iran to support Iranian Moslem revolutionary protest and propaganda efforts here.

Funds have been sent here from Iran through diplomatic pouches, international couriers and foreign banks, and also raised through the sale of hashish and heroin brought into the United States, informed sources said.

The money sent from Iran is part of an effort to export Ayatollah Ruhollah Khomeini's revolutionary Islamic ideology to other Moslems, defend Khomeini's regime and embarrass his critics, such as the U.S. government, sources said.

The money is used to transport, feed, train and recruit Iranian students and black American Moslems in this country, they said. At the heart of the movement, the officials said, is a cadre of perhaps 50 people whose dedication to the principles of the Iranian revolution includes, by their own words as published in mimeographed manifestos, harassing and even killing opponents.

Law enforcement officials say they have gathered the bulk of this information over the last 10 months. They have been confronted by an ever-increasing number of Iranian demonstrations here and elsewhere, and they have struggled to determine who the demonstrators are, what they want to achieve, and how they are financed.

The sources said that the money has been flowing into the United States for at least a year and possibly longer.

"It's obvious there's a hell of a lot of money going around" to support these demonstrations, said one law enforcement official. "You've got professional demonstrators, without jobs, traveling around the country, getting cars, buying property and paying for their living expenses."

Periodic pro-Khomeini, pro-revolution demonstrations have increased dramatically around the country in the last month, with Iranian Moslem radicals holding rallies in Los Angeles, San Diego and Denver, as well as here.Many have traveled across country to demonstrate.

According to the law enforcement sources, the collecting point for much of this money is an East Coast banking concern that has its principal offices overseas. They said that at least several hundred thousand dollars have been funneled through this bank.

Other funds have been sent into the country in Iranian diplomatic pouches sent through the Iranian Interests Section at the Algerian Embassy here, and through the sale of narcotics smuggled here, the law enforcement sources said. Since the United States broke diplomatic relations with Iran last spring, Iran's interests in the United States have been handled by the Algerian Embassy.

An Algerian Embassy employe who answered the phone yesterday said that no one was available to comment on the allegations.

All this information is said to come from informed sources in this country and abroad whose allegations have been independently corroborated a number of times, the law enforcement sources said. It is not clear, they said. how long specific amounts of money have been in the United States or precisely how the cash is distributed.

But the sources said they believe "beyond a reasonable doubt" that about $5 million has been sent here, some even after President Carter on Nov. 14 prohibited the entry of money from the government of Iran.

Law enforcement sources also say they are convinced that one of the chief local disbursers of funds, and the key coordinator of Moslem protests here, is Bahram Nahidian, a Georgetown rug merchant and the most prominent Khomeini supporter in the country.

Nahidian, reached for comment yesterday at the Islamic House at 5714 16th St. NW, denied the allegations.

"I am not the agent of Imam Khomeini," he said, "I am not providing the money at all."

Nahidian, according to law enforcement officials, has been recruiting black American Moslems to the Khomeini cause. His chief lieutenant, they say, was Daoud Salahuddin, who is accused of murdering the leader of an anti-Khomeini Iranian factor at his Bethesda home last month. Salahuddin, who is now reported to be in Iran, was paid between $500 and $1,000 a week while working for Nahidian. law enforcement sources said yesterday.

The group that Salahuddin belonged to, according to these sources, is known as the Islamic Guerrillas in America (IGA). According to one IGA flyer, the group espouses the destruction of its enemies "by any means, whether lawful or imperfect." Another IGA leaflet advises members to "not limit themselves to conventional guerrilla weapons, e.g. shotguns, handguns, gasoline bombs, but other weapons which can be utilized with relatively no noise factor, e.g. daggers, razors, solid steel clubs, etc."

Nahidian, whose name appears at the bottom of one leaflet, denies there is any such group. "There never has been any group, any organization that was shaped with any intention of killing," he said.

Law enforcement officials say the most radical group here consists of a hard-core of 50 IGA members, with hundreds of sympathizers, who demonstrate under various names and give various spellings of the names of their groups in order to confuse lawmen. The common denominator, they say is that the followers are pro-Khomeini.

The umbrella organization, they say, is the Moslem Students Association (Persian Speaking Group) which is the group currently demonstrating in front of the White House, and whose members made up the 192 arrested here July 27.

The intensity of the group's devotion to the Khomeini brand of Islam has fractured the normally placid Moslem community in Washington. Police say they are concerned with violence between Moslem groups and within the last week have warned two moderate Moslem leaders here that they have been reported to be on a list of people targeted for assassination.

Some law enforcement officials have maintained there were strong indications that the activities of pro-Khomeini groups in this country have been orchestrated in such a way as to cause the most embarrassment to the United States.

They have cited as evidence the discovery that all the pro-Khomeini demonstrators arrested here July 27 came from outside the Washington area and that an unusually low number were found by immigration agents to have violated the conditions of their entry into the United States. In addition one demonstrator told federal immigration officials that all the protesters were handpicked for arrest before the demonstration.

Behind these various activities, the law enforcement officials said yesterday, has been money coming from Iran.