Flyering Vehicles in the City of Los Angeles

I work for an event that requires me to flyer vehicles with info about a street closure and possible tow away if vehicles are left after a certain time. But someone, who apparently is on the city council, told me that flyering Vehicles is illegal. We only flyer vehicle along the proposed route that requires all vehicles to be removed by their owners or be towed.

Is it legal to flyer vehicle in this manner?

Flyering Vehicles in the City of Los Angeles