There is no doubt that Israel would attack Iran in a second if they thought they could win. However, it is extremely unlikely they would win without US support. So yes they want to attack and they keep saying they will do it alone but I don't believe. I don't think Israel will attack them without the US, no matter how much they want to. So all the US has to do is not attack, and make it clear we will not attack and peace will remain in the area.

As for Iran acting tough, they have to. If Iran was a smaller country they would have already been attacked. When the other side refuses to use diplomacy and only understands violence, such as the US and Israel, you have to be tough. It is the only thing they understand. That is why there is no serious thought on attack China or Russia, no matter what they do.