We did, until they invaded our Embassy. There is a level of fake, but necessary, politeness in international relations. But Iran has been using proxies to attack us for decades, so they can @!&$ right off. No need for this message, just. Ignore it.
I remember when we had diplomatic relations. I was in our Embassy in Tehran on Feb 14,1979 when the Mojahedin seized our embassy the first time. We were held hostage for a few hours, unlike what happened later in the year on November 4.
The Iranians were responsible for many U.S. deaths in Iraq. Iran trained Hizballah killed 241 U.S. military personnel, including 220 Marines, 18 sailors, and three soldiers in a terrorist bombing of the Marine Corps barracks in Beirut, Lebanon.
In 2006, a U.S. federal court found Hezbollah and Iran guilty of blowing up Kobar Towers in Saudi Arabia in 1996 that killed six Americans and two Indian citizens and injured about 70 others.
Blinken is an embarrassment. He still wants to revive the JCPOA.