Unlike raptors it takes a long time for their attack to damage you once they get in attack range, they have to charge their head back and then strike you which takes a little less than 2 seconds, they also stand still during this attack animation which gives you time to simply move out of the way.

Also you shouldn't use melee weapons against it cause it will deal 20% of the damage to you back through armor, and also severely damage the melee weapons durability. It's way more worth it to use crossbows or firearms.