Services to New York JFK and Orlando were due to start on 29 July but will now commence on 30 September. Flights to Barbados will start on 20 October as originally scheduled.
The carrier has set up a UK-registered brand to allow non-stop services from the northern airport.
It said: “Aer Lingus (UK) Ltd remains fully committed to its services from Manchester airport, and looks forward to launching to New York and Orlando on 30 September, and to Barbados on 20 October.
“Aer Lingus is sorry for any inconvenience caused to any of our customers.
“Our dedicated teams are contacting customers directly and offering a full refund, re-accommodation on an alternative service or a voucher for use across the Aer Lingus network over the next five years.”
