The politics of the situation may dictate a need for negotiation, but morally and legally there should be no negotiation between an opposition party which has won an election and the regime that is attempting to negate the result of it by violence. The agencies of international law are in hock to political exigencies, where a greater separation of the two is needed.
But a greater separation of politics from law, even if it were possible (I find that dubious), is not clearly desirable: if law is going to be useful at all to problems as they arise in international politics, then laws and institutions need to be formed with an idea of what they will look like put into the hands of actual states and political officials. In some ways, it's the separation of the two that's the problem. Consider a passage from today's NYT story:
The back-and-forth at the Security Council reflected the continuing debate over whether electoral crises constitute a threat to international peace and security, the main requirement for them to be taken up by the Council. The United States and others, including Mr. Ban, hold that they do, not least because of the humanitarian crisis caused by the Zimbabwean government’s decision to bar aid organizations from working in the country.
What's holding them back is an institutional structure that separates politics and law too much. The clear interest is in expressing concern over what's occurring in Zimbabwe, and contemplating steps beyond that, if necessary. But the politics must be held back and made to conform to the law. Separation, after all, can mean giving ascendancy to either the politics that prevent good responses, or the politics that make them possible; the law that hinders due concern for the rest of the world, or the law that makes it possible.