Trump was elected president because it was hoped he could clamp down on immigration and stop the mass exodus of American jobs overseas. There was also hope that he could scale back the never-ending conflicts in the Middle East and elsewhere. He certainly wasn't elected to start a war with Iran, anymore than Obama was elected to bomb Libya and overthrow Ghaddafi (and attempt to overthrow Assad).
A plebiscite for war with Iran would be soundly defeated by both Democrat and Republican voters. Yet the lobbyists, think tanks, State Department and Pentagon hacks, have been pushing for war with Iran for more than a decade and now see their chance. I really hope Trump has the stones and brains to say no, but I have my doubts.