I'm not naive enough to think that Israel won't act in its perceived national security interest simply because its actions might endanger Jews overseas. And I wouldn't like to see Israel paralyzed into inaction out of such a fear -- though, on this particular issue, the threat of the Iranian nuclear program, I'm far from convinced that Israel should act militarily.
The only thing that can be done is for Jewish institutions to prepare themselves for attacks that would almost certainly be launched in the wake of an Israeli strike. And, as of right now, the American Jewish community is not prepared at all.
An Israeli attack on Iran would take the religious war now threatening the planet to a new level of unpredictability and terror. No one would be immune from the consequences, least of all Israel, and Jews everywhere. This is not necessarily a reason to eschew it, if it could actually prevent worse consequences. But that case doesn't hold much water.