The opposition was relatively token. By 1961, decolonisation was in full swing, and France had already given up its similar enclaves. There was no real prospect of the west going to militarily aid a colonial power, especially one that had been a military regime for many years. If you're meaning coming to Portugal's aid as part of NATO, the treaty did not cover colonies, in spite of French attempts to include Algeria (and Portuguese attempts to claim Goa was sovereign territory). The situation was completely unlike in East Timor, as India was popular in Goa, having provided support for many years, and there were no violent recriminations after the conquest.

Additionally, did Goa want to remain independent? Also, why was there a massive uproar about East Timor and Indonesia; while, India kind of got away with this? (I don't know if I can ask supplementary questions here, nevertheless I want to try.)