A New York art importer who pleaded guilty to undervaluing $228,000 worth of pre-Columbian artifacts was sentenced yesterday to a one-year suspended sentence and a $1,000 fine in federal court in Alexandria.

District Judge Richard L. Williams also ordered David Bernstein, 35, to perform 200 hours of community service in New York City as part of his probation arrangement. Under his plea agreement, Bernstein had promised to cooperate with federal officials in a continuing investigation of pre-Columbian art imports.

Customs agents at Dulles International Airport seized the artifacts last year as part of an effort to end what some underdeveloped countries contend is a plundering of their national treasures. Bernstein ended a criminal investigation into his business by pleading guilty to a misdemeanor charge of filing a false customs declaration and by agreeing to return the seized items to Peru.

Prosecutors said that when Bernstein arrived at Dulles in January 1981, he said his suitcases held 66 Peruvian artifacts worth $1,785. Skeptical customs agents opened the bags and found precious pre-Columbian textiles, gold alloy death masks, a rare feathered poncho, and other items, all taken from ancient Peruvian graveyards. Federal agents armed with a search warrant later seized at least 160 other artifacts valued at $1.4 million at Bernstein's home in Manhattan.

Customs officials said early this year that Bernstein's guilty plea was the third in recent months in which American importers have agreed to return Peruvian ethnological art treasures.