The struggle for control of the Islamic Center Mosque on Massachusetts Avenue NW near Rock Creek was stalemated yesterday when prosecutors told a D.C. Superior Court judge they would not press charges against three Moslem fundamentalists who allegedly led a takeover of the mosque five months ago.

The dispute--between orthodox or militant Moslems, who continue to occupy to mosque, and the center's more moderate board of governors--erupted last October after the board ordered the mosque closed for several weeks to repair the building.

About a dozen demonstrators--allegedly led by Bahram Nahidian, an Iranian-American rug dealer in Georgetown believed by law enforcement officials to be the leader of Moslems here who support Iranian leader Ayatollah Ruhollah Khomeini--occupied the mosque.

The center's board alleged that the demonstrators intimidated the staff and the imam, or religious leader, into turning over the center to them. Two demonstrators, meanwhile, sued to stop the closing.

The center's board, made up of ambassadors to the United States from more than 40 Islamic nations, then filed a countersuit, and a Superior Court judge ordered the demonstrators to leave the building. When the demonstrators refused to leave, Nahidian and two others were charged with criminal contempt and the U.S. attorney's office was assigned to prosecute the case.

Assistant U.S. attorney F. Joseph Warin yesterday told Judge Robert A. Shuker that he wanted to "withdraw" the complaint "with the consent of the board of governors."

Shuker granted Warin's request, but reminded the defendants that his order to leave the center remained in effect, which means new charges could be brought. Lawyers for the defendants, however, have challenged the order as a violation of First Amendment rights.

Warin declined to say why the criminal complaint was withdrawn. Thomas Abbenante, Nahidian's lawyer, said the government dropped the charges because it had a weak case. "They just couldn't prove it," Abbenante said. "We're back to where we started from."

The board is now considering what other legal action it can take, said Christopher B. Hanback, an attorney for the board.