No it is not an act of war considering we are already at war with Gaza as they fire rockets at Israeli towns and cities, thats also why the UN have declared the blockade of Gaza to be legal. Also legal or not Israel will continue to send drones, I aim sure there are regular flights over Iran as Israel has opened an airbase in the Kurdish areas of Iraq where is has based a fleet of UAVS and I doubt they are there to see who is living in Saddam Hussain's palace these days. It sends planes into Lebanon and probably Syria. Send UAVS to Sudan to destroy an arms convoy. Wherever Israel thinks its in its best interest to spy it will spy legal or not. The real world is not the same as the legal world where we have rules on what can or cannot be done.
Declassified docs reveal Pinochet ordered 1976 assassination of diplomat in U.S. (AP)
from the article: Military drone crashes near central Israel town