Thanks for raising this inquiry for restricting access to tags. Unfortunately, I don't see a way to restrict tags out of the box. If this is an important feature you'd like to see in the future, I'd recommend submitting a feature request idea in the Ideas for Jive space to capture this use case. Otherwise, you may want to look into a Jive Professional Services (PS) engagement to look at customization feasibility.
Let me know if you have any other questions or would like to be put in touch with our PS team.
Thanks. I think I can live with this answer in the first place. It is not an important feature so far.