AFAIK, Iranis in India are an ethnic group of immigrants from Persia. Wikipedia says this about Iranis http://en.wikipedia.org/wiki/Irani, and from the very little I know about this through family connections, this sounds about right:
"Most Iranis are descendants of immigrants who arrived on the subcontinent during the 19th and early 20th centuries, that is, when Iran was ruled by the Qajars and when religious persecution of non-Muslims was rampant. The descendants of the immigrants of those times remain culturally and linguistically closer to the Zoroastrians of Iran, in particular to the Zoroastrians of Yazd and Kerman."
As I just found out when I looked up the Wikipedia article above, apparently Iranis are distinct from Parsis (Parsees), another ethnic group within India with cultural and religious (Zoroastrian) ties to Iran. Ancestors of today's Parsis apparently came to India over 1000 years ago.