The DUP's Peter Weir encouraged the assembly to issue "a clarion call" to to the government in London to withdraw its plans to limit tax relief on large tax donations, on 30 April 2012.
Mr Weir questioned the figures the Westminster government had quoted regarding the potential effect on charitable giving.
"The reality is that this will have a very significant impact," he said.
The North Down MLA added that "the government was wrong to put this forward".
Willie Clarke supported the motion on behalf of Sinn Fein.
He observed that the message seemed to be that these charitable donations were "some sort of tax fiddle".
The UUP's Leslie Cree was also supportive, saying that it would clearly disadvantage the work being done by charities at a difficult time.
Dominic Bradley of the SDLP said he hoped the Chancellor would take on board the views of the assembly, and Judith Cochrane of Alliance said the sad truth was that many donors would simply give less.
The motion was carried on an oral vote.