McClean opted for the Republic, despite being born in the province and representing the North at Under-21 level. He had claimed that, as a Catholic, he did not feel comfortable playing for Northern Ireland.
But angry Gillespie has hit back, telling McClean he was out of order.
"I think McClean was clutching at straws with those remarks and trying to come up with some sort of excuse," said Gillespie, capped 86 times by the North, in the Daily Star.
"I'm of the firm belief that if you're born in Northern Ireland, you should not have the option of playing for the Republic.
"James McClean is a prime example. He had no intention of ever playing for the Northern Ireland senior team.
"He made some excuses in relation to being a Catholic, but you look at some of our greatest and most capped players who are Catholic people like Pat Jennings, Mal Donaghy, Martin O'Neill and Gerry Armstrong."