The D.C. police department began an internal investigation yesterday to determine if any of its officers used excessive force to break up day-long protests by Iranian demonstrators Sunday. At least 35 people were injured during the protest, most apparently by police.

Dozens of club-swinging District and U.S. Park police pushed, shoved and struck the demonstrators with a frequency that reminded many of the May Day clashes of 1971. Some policemen reportedly removed their badges to avoid being identified. Television news films of the beatings, aired over the past two days, was reminiscent of scenes from the early civil rights demonstrations in the Deep South.

Maurice turner, assistant chief for field operations, said yesterday that no complaints of police brutality have been filed. But, Turner said, he has asked Deputy Chief Robert Klotz, who heads the Special Operations Division, "to look into the incident, to critique our handling of the demonstration because of the innuendoes of police brutality." Klotz was in charge of the officers Sunday.

Klotz said yesterday that he "personally did not see anything that I would consider excessive force, but of course I was not at every place." Klotz said in all cases of violence he observed, police were "actively confronted" by demonstrators.

After a viewing some videotapes of the demonstration, Klotz told and interviewer for WDVM-TV (9), "I don't see any obvious abuses. There was one shot in there involving the use of a nightstick on somebody who was already prone on the ground. That doesn't particularly thrill me."

Klotz said that in instances where police used force, it was justified in order to "make and maintain arrests."

Some of the scenes recorded in the television news film and observed by reporters Sunday showed:

On 15th Street, between F and G streets NW, a woman with tinted red hair was grabbed by a District police officer and encircled by at least five others, who beat her continuously on the head and body with two-foot-long wooden billy clubs.

At the southwest corner of 16th and L streets NW, across from the Capitol Hilton, more than 20 officers rushed a group of demonstrators and began beating them. One man fell and was beaten seven or eight times with a club by one officer before a white-shirted police official backed the officer off.

At 16th and K streets NW, in front of the Northwestern Federal Savings and Loan, a group of 15 to 20 police officers rushed a group of demostrators who apparently were not moving from the area quickly enough. As they began swinging their clubs, the Iranians tried to run, but were contained in a rough circle and beaten. Several men fell. One was picked up and then slammed down on a car, leaving blood from cuts on his head smeared on the hood.

Mayor Marion Barry, himself a former civil rights activist, said yesterday that "nobody has brought [the police action] to my attention.

"I wasn't at the demonstration," Barry said. 'I saw some news film clips . . . I wasn't watching very closely, so I don't know the extent of these allegations at all. I do know that there were at least two police forces down there, Park Police and metropolitan (D.C.) and I have not had any complaints filed with me. I understand that things got a little difficult," Barry said.

Police Chief Burtell M. Jefferson left on a trip to Taiwan before the demonstration, and was unavailable for comment.

A spokesman for the U.S. Park Police said yesterday that no complaints about police conduct has been made and that no investigation was planned. The television news film reviewed by reported showed no incidents of violence by park police.

Public response to the police action has been muffled, in part, some community leaders said, because many were hostile toward the Iranians, most of whom are supporters of Ayatollah Ruhollah Khomeini. Iranian militants in Tehran, with Khomeini's acquiescence, have held more than 50 American hostages since Nov. 4, and pro-Khomeini demonstrators have been booed, cursed and occasionally attacked in the streets of Washington.

"They have the constitutional right to deomonstrate, but they have done it so often that it grates on people's sensitives," said Bob King of the 14th Street Project Area Committee. "We still have 52 people over there. That's why people haven't really complained. . . . They see all Iranians through the same glasses."

Leslie Harris, executive director of the National, Capital American Civil Liberties Union, said the ACLU has not yet received any complaints about the incident.

"Certainly the police are human and I don't think they can be expected at all times to separate their personal animosities from their professional work," she said. "But we hope they would try, because otherwise certain segments of the community can't be guaranteed equall treatment by police."

About 1,500 Iranian marchers from four separate groups ralied in downtown Washington Sunday. The major demonstration was sponsored by the anti-Khomeini Iran Freedom Foundation, whose leader, Ali Akbar Tabatabai, had been shot to death at the front door of his Bethesda home the previous Tuesday.

The Freedom Foundation demonstration had been planned before Tabatabai's death, but three other groups, Marxist and pro-Kncmeini organizations, launched counter demonstratins at the Ellipse, Lafayette Square and at the Capitol.

When the rival groups refused to relinquish demonstration space to one another and when District and Park police felt the demonstrations were out of control, law enforcement officials waded into the crowds of protesters, arresting more than 200. At least 35 persons, including two policemen, were injured.

By yesterday, most of those arrested had been arraigned in D.C. Superior Court on disorderly conduct and assault charges, and were being held in jail. Most of those in custody, supporters of Khomeini who feared deportation, refused to give their names. The U.S. Immigration and Naturalization Service is threatening to deport those who do not cooperate.

One protester who became ill while in the Superior Court cellblock on Sunday afternoon is currently in serious conditin at D.C. General Hospital with what doctors have diagnosed as a respiratory ailment. Police said the illness was not related to his arrest.

Yesterday, about 50 pro-Khomeini students held a sit-in in front of the White House on what they said was the second day of a hunger strike protesting alleged police brutality Sunday.

"We did not intend to create any kind of violence [during Sunday's demonstration]," said Abbas Mansour, 24 a spokesman for the Moslem Student's Association. "It started from the police side."

Mansour also said that films his group took of the demonstration would he shown in Iran to show how the "children of Iran" have been treated in this country. That, he said, could have an adverse impact on the 52 American hostages there.

Bob King, civil libertarians and other neighborhood leaders said yesterday they were concerned about the conduct of police during the demonstrations because frayed police community relations due to allegations of police brutality have often contributed to civil disturbances.

"We have really got a problem and if something isn't done about it, it isn't going to improve," King said. "People don't want to negotiate any more . . . and if they don't negotiate and the police act the way they do, you don't know how things are going go."

Meanwhile, the search for Daoud Salahuddin, the Washington man accused of killing Tabatabai, continued to shift away from the Washington area yesterday.

The Washington field office of the Federal Bureau of Investigation said that the hunt for Salahuddin remains "a top priority" but it is depending more on FBI offices in other cities and "every other intelligence agency available to us."

A spokesman said that included the foreign offices of the FBI, Interpol, CIA and police agencies in friendly foreign nations.

Salahuddin, 29, who changed his name from David Belfield when he joined a Moslem sect, is accused as the triggerman in the assassination.