[devil's advocate] USA intervention seems to cause problems pretty regularly. Why not just stay out of it and let the dominos fall as they will? It's pretty inarguable that not messing around will cause problems, but what's to say intervening won't cause worse ones? In any case, is it genuinely our business what other countries do? Its inarguable that other countries don't affect us, but it's sometimes hard to see how it's the US's responsibility to do something about it [/devil's advocate]
Mostly, my argument is: if anyone can think of a better idea then I'd be willing to give that a try instead.
I think there are several reasons why not to stay out of it. I think letting the dominoes fall as they will would have a real possible chance of at least a regional war. I think that the West has military support obligations to one if not both sides, while other powerful countries that are not the West's enemy (yet, and I hope they never are and have no reason to dread being enemies except when things like this happen) have their own obligations to countries that have strong feelings against Israel.
As to causing worse results, I would be hard pressed to name many other than a terrorist attack upon warships at sea. I doubt Israel would be willing attack a flotilla under US protection. While they may be very unhappy with this action, I also believe it is necessary to stop the unquestioned support of Israeli actions and that it would be a stepping stone to better relations not only between Arab countries and the US, but also between Arab countries and Israel, due to removing the enabler that is unflagging US government support of Israel's current policies despite very practical and humanistic reasons to the contrary.
It's not always our business to affect what other countries do. However, in this instance, which is much more important than 'always' I might add, I think it is very, very much our business as both countries are closely allied to the US; not to mention the threat of a regional war breaking out in a region where we still occupy a country to my chagrin.
All this said, I would say it's not the US's responsibility. It's something that simply needs to be done. If the Chinese or Russians or a Euro country were to do it in the knowledge that they could stop strikes with their presence, that's fine with me. However, I am a citizen of none of these countries, so I nominate my own country's powerful navy to accomplish the task. In addition, the more the merrier I feel as far as countries willing to participate AFTER a powerful enough state to prevent strikes on the flotilla has signed on.