United States invasion of Panama - Wikipedia
https://en.wikipedia.org/wiki/United_States_invasion_of_Panama#Local_and_international_reactions
I believe, that primarily, in mid-December of 1989, most of the world and especially our country had completely different set of problems to solve, so that invasion was mostly ignored. The old socialist left was mostly leaving the stage in 1989 and the new left was not yet here and didn't probably view Manuel Noriega as good guy anyway. So few would protest it. But it was still part of the approximately 15 years era after end of Vietnam war, when USA interventions were limited and low profile (compared to eg. later Iraq wars or presence in Afghanistan). And also, the Grenada and Panama interventions followed the "Monroe doctrine"...
