The judge, the plaintiff and a gaggle of defense attorneys were all set to go, but the trial scheduled to begin in U.S. District Court here was stopped in its tracks yesterday because federal court officials are afraid they won't be able to pay the jurors unless they get more money from Congress.

That was the scene in the courtroom of Judge Louis F. Oberdorfer, where attorneys are trying to wrap up a lawsuit brought nearly 10 years ago by community activists who claim that the FBI played dirty tricks on their protest activities.

The only issue to be decided is the amount of damages the activists should be awarded. But the governing body of the federal courts suspended civil jury trials nationwide this summer because of cutbacks mandated by the Gramm-Rudman-Hollings amendment to reduce the deficit.

American Civil Liberties Union lawyers representing the activists maintain that the ban on jury trials is unconstitutional, while lawyers for most of the FBI agents involved have told Oberdorfer they are willing to go ahead without a jury, or bide their time until Congress loosens its purse strings.

Only one of the agents insists that his case be heard by a jury.

"It's just extraordinary," said attorney Anne Pilsbury, who represents one of the activists and told Oberdorfer she has 12 witnesses waiting to testify.

Pilsbury contends that if they go ahead with a trial for some agents without a jury, they will have to come back later and conduct a second trial when the ban is lifted.

Federal judges in some states have temporarily ruled against the jury restrictions, imposed June 16 to head off an anticipated shortfall in jury funds. Jurors are paid $30 a day, and the cutoff could affect an estimated 1,200 civil cases through September.

Oberdorfer, who has not ruled on the constitutional issue, has asked the federal Judicial Council here for an exception to the order so that his trial can proceed.

The case dates to 1976 when members of several protest groups filed suit against the FBI, the District government and D.C. police, claiming intelligence officers had conspired to disrupt their activities through infiltrators and phony literature.

In December 1981, a District Court jury awarded $711,937 in damages to the activists. But two years ago, the U.S. Court of Appeals dismissed the case against the District and city police because of insufficient evidence and found that the statute of limitations ruled out a claim against some of the FBI agents.

The higher court returned the case to Oberdorfer for a new determination of damages against the remaining agents.