The countries in middle east want Iran to be weak, not to fall.

I think that from the point of the neighbouring countries, Iran is fine as it is. Israel and the USA keep it in check, it is under sanctions, which are both beneficial for its adversaries.

If the regime in Iran were to fall, first of all you would have repercussions on the neighbors, (refugees and the like), and instability. But also, in the longer run, the chance of a more better government, which could make the country stronger than it is.