The incident happened at around 10am on Tuesday between junction 4 Lathallan at Polmont and Linlithgow Loch on the M9.
Forth Valley officers say the male was in a white van and hung out of a window and struck the windscreen of a white BMW 1 Series car, damaging it.
Sergeant Blair Rennie of Larbert Police Station said: “We are appealing for anyone who may have witnessed this incident to please contact us.
“The M9 is a busy stretch of road and we believe that a number of people may have seen some or all of this incident.”
Anyone with information should contact Police Scotland on 101 or anonymously via Crimestoppers on 0800 555 111.