The FBI has opened an investigation to determine whether police here used excessive force in arresting 192 Iranian student demonstrators July 27.

The probe, which is being coordinated by the Justice Department's civil rights division, was ordered after several news accounts of the demonstration raised questions about the behavior of some policemen, a department spokesman said yesterday.

D.C. police and U.S. Park police shared responsibility for controlling the demonstrations, but the Justice Department spokesman declined yesterday to identify either as a target of the probe, saying only that the FBI is "investigating possible instances in which the civil rights of some individuals might have been violated" during the arrests.

Meanwhile, D.C. police officials revealed yesterday that through the U.S. Attorney's office here they are investigating the possibility of subpoenaing film footage of the demonstration in the possession of local television stations. The officials said they began considering the move when their requests for copies of the film were denied by the television stations last month.

At least 35 persons were injured during the protests, most apparently by police, witnesses said and film footage appeared to show. During the demonstration, some policemen reportedly removed their badges to avoid being identified.

Following the broadcasting of the film footage by local television stations, the D.C. police department set up two separate investigations into the conduct of its officers during the demonstration. Deputy Chief Robert W. Klotz, since retired, viewed WDVM-TV film clips in the station's studio within a few days of the demonstration, but said at the time, "I don't see any obvious abuses."

He noted, however, that "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."

Subsequently, District police requested that local television stations turn over their film voluntarily, but the stations refused, police said.

"We set up a committee to investigate allegations and innuendos that the department used excessive force on some of the demonstrators during the protests," Assistant Chief Maurice T. Turner Jr. said yesterday. "This is an on-going investigation. So far we haven't had one single complaint" from individuals allegedly beaten by police.

"If the investigation shows any malfeasance, we will take appropriate action," he said.

A spokesman for the U.S. Park Police said last night that so far as he knew, his department had not initiated any investigation into the conduct of its men during the demonstration.

Justice Department spokesman John V. Wilson said yesterday that the federal investigation is "in the early stages. It takes quite a while." He said it would "probably" be months before it is completed.

Wilson said that shortly after the Justice Department ordered the investigation, "we received one complaint. We haven't received any others."

The demonstration, arrests and subsequent transfer of the 192 Iranians, all of them supporters of Ayatollah Ruhallah Khomeini, to New York jails had prompted outrage from the Iranian government. Khomeini at one point charged that the jailed demonstrators were being tortured.

Although the public attention attracted by the demonstration and jailings has died down in Iran since the students were released, any federal investigaion into the alleged beatings is likely to be closely watched by officials there, where the fate of 50 Americans hostages still hangs in the balance.

Thomas Shack, an attorney acting on the instructions of the Iranian government, said he filed a complaint with the Justice Department on Aug. 1, charging the local law enforcement authorities violated the constitutional rights of the July 27 demonstrators and demanding an investigation.

Shack, a partner in the firm of Abourezk, Shack and Mendenhall, said yesterday that the complaint alleged that news media film and eyewitness accounte "leave no doubt" that the students were "illegally assaulted, illegally arrested and otherwise deprived" of their civil rights.

Shack said the firm is acting on the instructions of the Islamic Republic of Iran through the Iranian Interests Section of the Algerian Embassy here. The Iranian government is demanding an investigation and the prosecution of the U.S. Marshal's Service, the D.C. Department of Corrections, the U.S. Park Police and the D.C. police department, all agencies that participated in either the arrest or processing of the demonstrators.

The demonstration involved about 1,500 Iranian marchers from four separate groups. 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 a few days before.

The Freedom Foundation march had been planned before Tabatabai's death, but three other groups, including both Marxist and pro-Khomeini organizations, decided to hold counter demonstrations the same day.

When the rival groups refused to move on, District of Columbia and U.S. Park Police waded into the crowd of protesters. At least two policemen were injured in the resulting melee, police said.