From 2007:
"But Iran, which has had diplomatic relations with the Holy See for 53 years, may be trying to line up Benedict as an ace in the hole for staving off a potential attack in the coming months. "The Vatican seems to be part of their strategy," a senior Western diplomat in Rome said of the Iranian leadership. "
Iran has a surprisingly large diplomatic corps at the Vatican (only the Dominican Republic has more diplomats accredited to the Holy See) who have a monthly meeting with papal advisers.
But other unofficial discussions, in trattorias and cafes and a variety of Church institutions, are a constant part of the diplomatic workings in Rome. And over recent months, the conversations have centered on the looming showdown over Iran's nuclear program.
http://content.time.com/time/world/article/0,8599,1687445,00.html
https://cruxnow.com/church/2016/01/26/the-bond-between-the-vatican-and-iran-is-a-partnership-destined-to-endure/