I use dynamic pvp which uses zone manager, and in a zone with the flag: undestr, helicos tanks etc also become indestructible not only buildings.
Do you have a solution?

I've have added a seperate flag 'NoBuildingDamage' which will prevent players damaging building blocks in the upcoming version. There is a beta of it out for testing if interested 
https://umod.org/community/zone-manager/44117-310-beta 

nice thank you ; )