Premises: 1) There exists another intelligent species in the galaxy. 2) Said intelligent species is technologically advance enough for space travel. 3) Said space travel method used by intelligent species other than mankind allows them to travel thousands of light years in relatively short time. 4) Said thousands of light years in relatively short time puts Earth within range. 5) They come in ships and initiate contact with Earth.
Question: Approach with caution or assume there is absolutely no reason for them to be agressive toward us and therefore just allow them to come down to our world and do whatever?
Since you've led the horse to water, the answer is obvious. That's like saying if I put a loaded gun to your head, would you rather me pull the trigger or not?
Isn't the answer obvious? It was in your question too.
"Political correctness is tyranny with manners." -- Charlton Heston