The Day the Earth Stood Still that came out in 2008 was kinda like you said. But it was a pretty bad movie, there is hardly any point in the plot. It's pretty much just fancy CGI effects and nothing else to the movie. If you ever watch The Day the Earth Stood Still, watch the original that came out in 1951. That is the best version of the movie. The 1951 version is a slow movie with hardly any action at all but it's a classic, so it's worth watching. Btw the two versions of The Day the Earth Stood Still have totally different plot points. The 2008 version is kinda like what you said in the OP, while the 1951 version is way different than the OP. The 1951 version is about an alien who comes to our planet and not about aliens already living here without us knowing. I give the 2008 version 1/5 stars while I give the 1951 version 3/5 stars.
Here is a movie that is really close to the OP AND it's a good movie. It's called The Arrival, it came out in 1996 and the plot is pretty well done (Depending on your point of view.). It's an overall good movie. The special effects wasn't that bad and it had some really interesting stuff happen. I give The Arrival 4/5 stars.