It would not be something like "attempting to disarm a lawful civilian" or something you've never heard of, it would be a more common crime and depends on the case. Almost every case I can think of (assuming the attempted disarm is unlawful) would be assault (any unwanted touching or an action that makes a person feel threatened for their safety). Maybe assault with a deadly weapon depending on the case. If you can prove that the person had intent to use your weapon on you, they could be looking at attempted murder charges. That's in the most extreme case.
This has happened before, but not in MI. It happened in Georgia. Thankfully I have saved the link to the thread: http://georgiapacking.org/forum/view...p?f=26&t=40381
So to answer your question, yes, a law exists, it is a normal crime, assault. The person would be arrested and charged with assault and any other applicable charges.