It's hard to say for sure. The first raids using military like tactics were carried out in Humboldt County, CA against "hippies". Now John Ehrlichman did tell Harpers Magazine in 1994 that in 1968 they intended to target " the antiwar left and black people," so there is that. But if you read through contemporary commentary from the 1970s you'll find a politically and racially diverse coalition in support of drug laws. Were some of them animated by racial animas, almost certainly, but it's not that simple. Charles Rangel, the then head of the Congressional Black Caucus whipped for the passage of strict drug laws as early as 1968.
The average American in 1970 really wanted more drug enforcement as an ends unto itself. It was something of a national preoccupation across the political divide by 1980.