An accused Shiite Moslem terrorist, who officials said was arrested after being tricked onto an FBI-rented yacht in the Mediterranean, was brought to the United States yesterday to stand trial for hostage-taking.

Fawaz Younis, 28, an alleged ringleader of the 1985 hijacking of a Jordanian airliner with four Americans aboard, pleaded not guilty in a tense 10-minute hearing before U.S. Magistrate Jean F. Dwyer at the federal courthouse here. Marshals, some with automatic weapons beneath their jackets, ringed the courtroom, then took Younis back into custody at an undisclosed location.

Dressed in a black overshirt and black pants rolled up at the cuffs, Younis spoke only twice during the proceeding, indicating through an interpreter that he could not pay for an attorney. Occasionally he looked up at Dwyer as she explained his rights.

Attorney General Edwin Meese III, meanwhile, announced the unprecedented apprehension to reporters at FBI headquarters. Meese called the arrest a "unilateral action by the United States" and "an important step in our policy of bringing terrorists to justice."

Younis, who is Lebanese, was charged in a five-count indictment with conspiracy, destruction of an aircraft and hostage-taking, under recent legislation giving the United States "long-arm" jurisdiction over offenses committed outside the country if U.S. nationals are taken hostage. The hostage-taking count carries a maximum penalty of life in prison.

Meese refused to take questions and turned over the session with reporters to senior Justice Department officials who said they were reluctant to spell out details. But they outlined what amounted to an FBI "sting" operation. Sources said it was dubbed "Operation Goldenrod."

Younis, they said, "voluntarily" came aboard a vessel that was rented and crewed by FBI agents. He was arrested in international waters on a warrant issued in Washington last Friday, the officials said. He was then flown to this country in U.S. military aircraft, arriving at Andrews Air Force Base early yesterday. The indictment against him was returned by a federal grand jury here on Tuesday.

The hijacking took place on June 11, 1985, when five Shiite Moslems armed with hand grenades and other weapons seized control of a Royal Jordanian Boeing 707 jetliner at the Beirut airport. They forced the crew to fly the plane, with about 70 passengers aboard, to Cyprus, Tunisia and Sicily before returning to Beirut the next day.

The hijackers demanded removal of all Palestinian guerrillas from Lebanon, severely beat several Jordanian skymarshals aboard the plane, and at one point said the passengers would be killed one by one unless their demands were met. At a news conference, one of the hijackers, identified as Younis, threatened to "deliver the corpses" to an Arab League leader they wanted to speak with.

Eventually, however, the terrorists blew up the plane after releasing all the people aboard, and escaped into the Shiite-controlled suburbs adjacent to the airport.

The hostages included two American citizens -- Landry T. Slade, a professor at the American University of Beirut, and his teen-age son -- and two other American "nationals" whose names were not immediately available, officials said.

In his statement, Meese said he wanted to emphasize that "acts of terrorism are criminal acts, pure and simple" and must be dealt with as such.

"As President Reagan has said, terrorists throughout the world must know that 'they can run, but they can't hide,' " Meese said. He said Younis' arrest was "the first such operation, but it will most certainly not be the last."

At the courthouse, Younis' court-appointed attorney, Frank Carter, asked Dwyer to postpone the bond hearing until Tuesday so he can learn more about the way his client was brought to the United States. He also asked that Younis' dietary restrictions as a Moslem be respected.Staff writer David B. Ottaway contributed to this report.