From one side, not all protests were against the national government, some if not most, were and are usually against the Buenos Aires City government (which is not peronist), or against some other government. You must take into account that Buenos Aires is a city with a high concentration of institutional buildings. So everything is in Buenos Aires. There’s this old saying in Argentina “God is everywhere, but his offices are/he only attends in Buenos Aires”
On the other hand, the peronist party is a highly fractured party. It’s more like a coalition of different minded individuals, that gather around the caudillo in turn. That’s why Perón himself said “peronists are like cats, when you hear them screaming, they are not fighting, they are matting”. Once the caudillo is in power, he must maintain it, and strength demonstrations are usually in the form of “getting the street”. Meaning, making a ruckus and sending people to protest. This goes for both sides, sports and detectors.
So, as you can hopefully see, Argentina’s politics aren’t as straightforward as thought.
The UN is not a military defense organisation la NATO. It has military efforts, but they are all Pacific in the sense that they don’t take part and only help the civilian population (e.g.: running medical and food supplies, or protecting hospitals, etc.)
The UN could go for economic and political sanctions, or try to move this in the Hague Courts in case the request goes unheard.