The US likes to play "hero". They want to be seen as the "knight in shining armor", helping damsels (countries) in distress. Problem is, not every damsel wants to be rescued. The US is somewhat akin to its current president in that it suffers from an inflated ego. It sees itself as the (self-appointed) sheriff of the world. If something happens in another country that the US doesn’t approve of, it believes that it’s its duty to intervene (must make the entire world just like the US).
When the US intervenes, it always claims that it’s doing it for “humane purposes”. As if saying that makes their interference legitimate. Sometimes they truly may be helping, but other times they intervene just to flex their muscles. “We’re a superpower in this world and don’t any of you forget that!” The US also thinks that every country in the world should have a government like theirs. Of course, not all countries agree with this, nor is it always feasible. By forcing “their way” on other countries, the US has become somewhat odious in the eyes of the world. Of course, no matter what they do, some other country (or countries) will disagree with them - and may even want to retaliate.
The bottom line is this - should the actions of one nation be of concern to other nations? What if they kill their own citizens? What if they develop nuclear technologies? What if they invade a neighboring country? What if they drop bombs on another country?