Which countries are likely to support India if it had a war with Pakistan or China?

The answer to this is in two parts since the war with Pakistan and the war with China will be two different scenarios.

War with Pakistan:-

We can definitely count Israel and Russia to side with us since we are the largest entity to trade with them in terms of weapons and ammunition.

All the ASEAN and SAARC countries will partner with us since they view India as an upcoming force in Asia, second only to China.

The conflict lies in the interest of the US. Since the inception of Pakistan it has garnered significant support from the USA in every sphere, especially arms and ammunition. But keeping in mind the ''war with terror'' of the US and the internal conflict in the Senate upon the decision to sell f-16s to Pakistan, America can go either way. 

War with China:-

Again, Russia and Israel in our camp.

This time around, US will also support us since they are already vary of China's increasing hegemony in Asia and they would do anything to keep it in check.

Here, the problem lies with the ASEAN and SAARC countries. Although they do look up to India, the fear of China in these countries is too great, as was evident when they refused to make India a permanent member of ASEAN.

And needless to say, Pakistan and China would support each other irrespective of the party at war.

source : quora.com