What Obama is apparently unaware of is that we're already at war with Iran.
Hundreds of Americans have been killed by Iranians or Iranian proxies. Iran has provided safe haven for Al Qaeda leaders for years. Iran funds international terrorism and has gone so far as to bomb a synagog in Argentina to kill Jews. Iran calls for the destruction of the United States.
Apparently Obama confuses not fighting back with not being at war.
At the present time there are multiple options for dealing with Iran ranging from keeping the sanctions in place to overthrowing the regime.
The one option we don't have is to avoid war because the Iranians are waging one against us so like it or not we are at war.