Nope, the atmosphere was specifically created to make you question what you were doing as the player.
Though I do feel the need to say: All the colossi WILL attack you on sight, the only exceptions off the top of my head being Avion (The first flyer) who attacks when you fire arrows at it, and Phalanx (the second flyer) who doesn't actually attack at all. A lot just happen to be slow and you can get to them before they get the chance (the first two are prime examples).