Nice try. But at least you looked it up, as did the OP, who just last week was saying that Iranians were Arabs.
Aran (Aryānām) became known as Persia courtesy of Alexander the Great (or as Iranians call him, Alexander the Greek, not being exceedingly fond of him for obvious reasons) who conquered and consequently ended the Empire. The largest tribe/ethnicity & province being Pars, the Greeks called it Parsa, Land of the Pars. From Parsa then came Persis, and from that it later became known internationally as Persia.
Iran had never changed its name though, other then the slight spelling, as already pointed out. That was still the name that it went by internally for over two and half millenia since Alexander.
In 1935 Reza Shah asked foreign countries and the League of Nations to call it by its proper name, Iran, instead of Persia. That's where the misconception of a name change came from.
Hope this clarifies things.