The DUP has said the public sector strike on Wednesday could cost the economy an estimated £500m.
East Antrim MLA Alastair Ross made the comments after Sinn Fein Education Minister John O'Dowd said he would not cross the picket line during the strike.
Mr O'Dowd said he supported the strikers but appreciated the disruption it would cause.
Mr Ross said the trade unions' approach would "damage the economy".
He said it was regrettable that they had decided to opt for a "show of strength" rather than engaging with the Stormont Executive on the issues.
"The action that will take place on Wednesday will hit the most vulnerable people, the people the unions claim to be sticking up for," he added.
Thousands of teachers and public sector workers plan to walk out on 30 November over cuts to pensions and budgets.
The DUP has said its assembly members will be at work as usual on Wednesday, but the SDLP said none of its MLAs would cross the picket line.
The UUP said it respected the right to strike but hoped that Stormont would continue to function to full capacity on Wednesday.
It said its leader would chair a committee meeting at Stormont on Wednesday, but that the decision of attending work would be left up to individual MLAs.
A number of teaching unions, including the National Association of Head Teachers (NAHT), are taking strike action.
A week ago, members of the Unite union employed by Translink voted to join strike action - meaning bus and train services could be severely disrupted.
A number of other unions have also voted in favour of the stoppage.
In Unite's three main aggregate ballots of health, civil service and local authority workers, 75% of Unite members voted in favour of action on a turnout of 31%.
More than two million workers across the UK are expected to join the strike over changes to public sector pensions.
Peter Bunting of the Irish Congress of Trade Unions said on Friday that there were no signs of an economic recovery and "somebody has to take action".
"The economy is at a standstill and it has been at a standstill for three years while these cuts have been implemented with the acceptance of the politicians at Stormont," he added.