my understanding is that international laws are set so that humans do have rights due to their conditions of being human, based on the assumption that there are things that you cannot do, regardless of the culture you live in. It aims at invalidating the idea that I can only articulate as "that is how things work in this country". For instance, you cannot annihilate groups of people based on religion, that is a crime, internationally, even if your country allows it.
That said, and again, these are individual rights. You can't condemn Rwanda for the crimes committed by their leaders: these leaders are put on trial.
It occurs to me that the US has sanctioned Iran and other countries (not an expert) in the past/present (again, not an expert). But that isn't international law: those are unilateral decisions made by the US government.
I can see both things occurring, but not intertwined. Could you please expand on what you understand by "people do have rights"?