INDIANAPOLIS (AP) _ For nearly two years, the Cypriot government mistakenly believed four sixth-century Christian mosaics stolen from a Cyprus church had been destroyed, the press counsel at its U.S. embassy testified Wednesday.

''In early 1980 we received a communique from Cyprus to the ambassador that the mosaics were destroyed,'' Marios L. Evriviades testified in federal court. The government, therefore, did nothing to recover them, Evriviades said.

But the mosaics were removed and sold for $1.2 million to Peg Goldberg, an art dealer from suburban Carmel. She is being sued by Cyprus and its Greek Orthodox Church, which claim they are the legal owners of the mosaics and want them returned.

Goldberg's attorney, Joe E. Emerson, maintains the plantiffs did not make a legitimate effort to notify the public of the theft and that his client has made a legal purchase.

Evriviades testified before U.S. District Court Judge James E. Noland that he learned in June 1982 that the mosaics had been removed and taken out of Cyprus.

''I drafted a press release about the theft to put people on notice that the rare mosaics had been stolen,'' Evriviades said.

The mosaics once graced the walls of a church in the northern village of Lythrankomi, in Cyprus, which has been occupied by Turkey since 1974.

The mosaics purchased by Goldberg depict Jesus as a boy, the apostles Matthew and James, and an archangel. The plaintiffs in the suit obtained a 90- day restraining order March 26 to prevent Goldberg from selling the artworks.

Goldberg purchased the mosaics from Aydin Dikmen, a Turk living in West Germany. Analysts have said the case could set a precedent governing international trade in national art treasures.

Athanasis Papageorghiou, acting director of Cypriot antiquities, testified under cross-examination earlier Wednesday of his agency's effort to recover items that were in territory occupied by the Turks.

He reviewed a list of 28 ''specialists in Byzantine art'' to whom Vassos Karageorghis, who headed the department of antiquities until May 1, had written about possible thefts in territory controlled by the Turkish government.

When Emerson asked why Cyprus had not notified the international police agency, Interpol, to investigate the alleged thefts, Papageorghiou said: ''We didn't have information about who the smuggler was and his address, and we didn't have exact descriptions of the objects. You need this to notify Interpol.''

Emerson also questioned Evriviades about his agency's efforts to obtain possession of the mosaics, bringing out that it had not notified the International Federation of Art Dealers, U.S. Customs, the Art Dealers Association of America or Interpol that someone might try to sell them.

''Are you aware that the view of the Turkish Cypriot government is that church property left behind by Greek Cypriots belonged to the Turkish Cypriot state?'' Emerson asked.

Evriviades said he did not and also pointed out that his government does not recognize the Turkish Cypriot state or its policies.

Emerson argued in his opening statement Tuesday that before Goldberg bought the mosaics, she tried to learn whether they had been stolen.

The case could rest on whether Cyprus diligently sought the return of the mosaics and whether Goldberg showed good faith in trying to determine if they were stolen.