Last time their missiles were mostly shot down. IMO Iran is just a roaring tiger who threatens more and do very little but still dangerous when cornered. Israel can exploit this time to form again a collision which will take down successfully the missiles when they'll launch their attack, and Iran will hunker down again telling their populace how successful their attack was. Going on the offensive with a major all out attack is extremely dangerous when dealing with jihads. Remember that shooting down short range missiles is much harder and they can send a barrage of thousands of these from Lebanon all over Israel C"V.
We don't have the right insight to know what the "right" decision is, but it definitely can't be taken lightly. Fighting an enemy that doesn't respect international law makes it much harder, especially when you're expected to uphold to a standard of international law that does not exist. A coalition would be ideal, but is unrealistic at this time when the West refuses to recognize their enemy.
I used to think that "Know thy enemy" meant to learn their tactics, their strategies and put yourselves in their shoes and understand their train of thought. Now, I see it as simply saying to just recognize your enemy and know who it is and act upon it. Its unbelievable to see what is going on and is so easily preventable.