Alexandria lawyer James I. Burkhardt pleaded innocent yesterday in federal court in Alexandria to three counts of racketeering and conspiracy in connection with alleged cash payments to unnamed public officials to "buy protection" for a large Washington area prostitution ring.

Judge Albert V. Bryan Jr. in Alexandria scheduled Burkhardt's trial for March 31, with motions to be heard on March 14. Bryan released Burkhardt on $5,000 personal recognizance bond.

Burkhardt, 49, was indicted Tuesday by a federal grand jury on charges that he assisted convicted message parlor kingpin Louis Michael Parrish in the organization and operation of Parrish's $1 million a year prostitution operation.

According to the indictment, Burkhardt, a former president of the Alexandria Bar Association, was given money by Parrish to buy protection from various Alexandria and Virginia officials. A lawyer for Burkhardt has said prosecutors are trying to prove that former Alexandria Commonwealth's Attorney William L. Cowhig was one of the officials involved, an allegation the lawyer said was untrue. Prosecutors have declined comment.

From 1974 to 1978 Burkhardt instructed Parrish employes on how to avoid prosecution for illegal activities, withhold information and lie to officials to protect the operation, according to the indictment.

If convicted, Burkhardt could face 15 years in prison, a $15,000 fine, and automatic revocation of his license to practice law in Virginia.