It's not avatar and it was thriller/horror from the 80's.
Fifi Rodriguez goes to Hawaii?
A little less description would help. -please note the sarcasm-
"The People Under the Stairs?" I haven't watched it in a while, but wasn't there a blue tinge to their skin?
Full description:
A couple is seen enjoying themselves in the forest (they weren't making sex, if that's what you think - they were chasing each other between the trees). Suddenly a big stone/rock falls from a tree. It is tied to a rope or something to the tree. The blue people are the ones trolling the stones. The couple started running away in the woods and found a cottage or something. They hid inside the house. I don't remember what happened next.