More than 400 blacks paraded past hundreds of angry whites lining a street in New York where two blacks allegedly were beaten by a gang of whites on Christmas Day. The marchers, chanting "no justice, no peace," were separated from the whites in the Bensonhurst section of Brooklyn by hundreds of police officers, many of whom wore helmets and carried night sticks. There were no arrests and no injuries were reported. Yells of "Go home" and "Howard Beach" were heard above the din as whites, some carrying signs, stood on cars and shoulders along the blocked-off street. In an attack on Dec. 20, 1986, in the Howard Beach section of Queens, a gang of white youths beat a black man and chased him onto a highway, where he was killed by an automobile. Three teen-agers were convicted of manslaughter last month in that case. Police have made two arrests in the Brooklyn attack.