Irish people were definitely enslaved... in the early medieval period and earlier, but it was mostly done at the hands of other Irish people for the benefit of Irish people. The notion that the Irish were systematically enslaved in the early modern period is an insidious myth usually toted by white supremacists to denigrate the experience of enslaved Africans and their descendants.

This is a recurring myth and is covered in the FAQ. Liam Hogan from Limerick has an excellent essay here https://www.academia.edu/9475964/The_Myth_of_Irish_Slaves_in_the_Colonies on it.