99% of Americans know almost nothing about Venezuela.
Almost nobody in America was calling for the US government to interfere with Venezuela's internal politics except for a tiny minority of swamp creatures in imperial cities from across western civilization.
This is pure aggression on the part of the US government. They haven't even bothered to articulate a defensive pretext for their hostility towards Venezuela, just like they didn't bother with Syria.
As for your question about the US-backing the opposition in Venezuela, I think that pretty much goes without saying. Any country that is the target of US sanctions is being subjected to a nonstop covert "regime change" operation, part of which involves organizing and militarizing a domestic opposition.