I suspect this 'attack' was a surprised bird crashing or narrowly swerving to avoid a high-speed cyclist. Possibly a freshly fledged juvenile. I was once "attacked" by a Woodpigeon when cycling. It flew from the side in the completely open place with good visibility. It hit me in the face and it was quite painful.
Otherwise - as Kennethwwfd pointed, a fearless buzzard would become an attraction to photographers from far and wide.