Iran has never attacked Israel unless attacked first. As for their 'proxies' they only really exist because Israel has invaded Lebanon long before Hezbollah existed and its creation was spearheaded primarily by Lebanon's local population as a response to the invasion, with Iranian support.
Iran supports these local 'proxies' because it sees itself as a leader of the Shia and more broadly as a leader of the Muslim world and the Palestinian cause as being the responsibility of every Muslim nation (incl theirs) to get involved with.
Israel is indeed concerned with Iran as a threat, but only because they see the other governments in the region as willing to overlook the Palestinian cause, in exchange for economic links with Israel.
In that sense Iran is very much connected to the Palestinians, this assertion that Iran is just super irrational and wants to see Israel go down because they want to laugh watching it or something is nothing more than cheap Israeli propaganda.
Of course Iran is not just looking for the Palestinians out of altruism, they want a leadership position in the Muslim world and this is their way of gaining legitimacy, but the reason why Israel sees them as a threat is very much because of Iran's interest in the Palestinians.