If you're asking in good faith, Israel isn't attacking Iran to play world police. Israel has been under constant attack from Iran-backed proxies. As for why Iran backs these proxies, the answer boils down to pure fanaticism. For a fanatic-led state to possess nukes is a dangerous situation and it's worth it for Israel to try and prevent it.
As for why America is involved in a conflict between Israel and Iran, it's because we have a Republican administration and a big segment of Republicans (Christian Evangelicals) want the US to ensure Israel as a state survives (also for purely fanatical reasons).
As for why America is involved in a conflict between Israel and Iran, it's because we have a Republican administration and a big segment of Republicans (Christian Evangelicals) want the US to ensure Israel as a state survives (also for purely fanatical reasons).