Collins:
GENOCIDE: the policy of killing a nationality or ethnic group
Chambers:
GENOCIDE: The deliberate extermination of a racial, national, religious or ethnic group
Webster:
GENOCIDE:
The use of deliberate systematic measures (....including killing ...) calculated to bring about the extermination of a racial, political or cultural group or to destroy the language, religion or culture of a group
etc
So I think that clears one up. Plainly the Russian justification is a load of rubbish, as it has been pretty well demonstrated that in fact NOT calling it genocide has had the exact opposite effect. as we have seen with the reaction of some to the appearance of the Serbian PM in Srebrenica.
Trying to find other reasons, it seems to me, is simply playing the Russian game. More interesting are the real reasons why they don't call it such:
one would be that the Serbs themselves have not done so, and they don't want to upset them (perhaps that is what is meant by "greater tension")
Another would be that they would fall over backwards not to support any resolution proposed by Britain or the US about just about anything.