DSTAVERT is correct; you may have to do this via the guest and avoid VMDK-level cloning. I don't see other options, unfortunately.
Converter allows live conversion from within the guest in most cases (treat it like a P2V), but be aware of any potential differences between the destination copy and your original. I believe the destination is only as current as the immediate moment you start the cloning process, but someone can feel free to correct me.