The country star was scheduled to play five sell-out gigs at Croke Park from 25 to 29 July, but Dublin City Council has ruled that two cannot go ahead.
There have since been newspaper reports that some councillors are in favour of offering Stormont as a potential venue for gigs, but Belfast City Council has stressed there has not been an approach.
A spokeswoman for the council said: "At this time there has been no formal approach to Belfast City Council about the possibility of hosting Garth Brooks concerts in the city."
Meanwhile an emergency motion is to be presented to Dublin City Council by Sinn Féin on Monday calling for the five Garth Brooks concerts in Croke Park to go ahead.
Mary Lou McDonald, the party's TD for the area covering Croke Park, said the situation has been badly managed on many fronts and she has urged the decision to be reversed.
Dublin City Council has previously stated its decision cannot be amended or appealed.
Garth Brooks said it will be "five shows or none at all", but concert promoter Peter Aiken remains hopeful that all five can go ahead, with a final decision expected by Tuesday.
Meanwhile concern is growing that the economy in Dublin could lose up to €15m if the gigs do not take place later this month.
Donall O'Keeffe of the Licensed Vintners Association said: "This is still a very difficult economy for every business in the city and the Garth Brooks concerts promised a hugely significant financial boost for pubs and for the wider hospitality industry.
"Our members need clarity on this as a matter of urgency."