As soon as you see the message, immediately drop what you are doing and run for the nearest rock or other high ground where they can't reach you.

Large rocks with steep sides, big logs with branches you can stand between blocking them from getting to you, etc.

If you are mining a location, or collecting wood or some other resource in a particular spot for an extended amount of time, build yourself a platform ahead of time in a big tree.

Preferably an indestructible one in the environment. Or even up the side of a big rock on a steep side. You can snipe them to death or simply wait out the event.

You can also stun them with a melee weapon blow. Use a shield to Parry ( Parry capable shield) (They do 2 or 3 fast strikes. Get use to timing)