Aaron R. Frosch, a lawyer for stage and screen actors, died yesterday of cerebellum atrophy, a neurological disease, at his home in Manhattan. He was 64 years old. Mr. Frosch's clients included Marilyn Monroe, Richard Burton, Elizabeth Taylor and Margaret Leighton. Born in Brooklyn, he graduated from Brooklyn College and Brooklyn Law School. He joined a Manhattan law firm, then began his own practice in 1973. He retired in 1981, when he fell ill. Mr. Frosch was a former vice president of the Rebekah Harkness Foundation and the William Hale Harkness Foundation, which supported the dance. In 1967, he was co-chairman of the Mayor's Committee for the Shakespeare Festival. Surviving are his wife, Bobbie; three daughters, Juliana, of Charlottesville, Va., Phoebe, of Alexandria, Va., and Suzanna, of Piermont, N.Y.; his mother, Anna H. Hollander of Manhattan, and a brother, Samuel Hollander of Roslyn, L.I.