Unfortunately the answer is yes. Battery on a peace officer under California law, Penal Code 243(b) or 243(c) PC, is a crime even if the officer isn’t injured.
The same thing is true of simple battery under California Penal Code 242 PC. A “battery” is any harmful or offensive touching of another person–it doesn’t have to cause an injury of any kind.
But there is some good news. Under PC 243(b), battery on a peace or police officer that does not cause injury carries only California misdemeanor penalties. The maximum sentence for battery on a peace officer without injury is up to one (1) year in county jail, and the maximum fine is two thousand dollars ($2,000).
(In contrast, battery on a peace officer that does cause injury is charged under Penal Code 243(c)(2) PC and can carry felony penalties, including a much longer jail sentence.)