Liberal Democrat MP Adrian Sanders tabled an Early Day Motion last week stating the Public Fundraising Regulatory Association "does not operate any serious regulatory standards".
He urged local authorities and retailers to be cautious when dealing with the organisation whose main functions, he claimed, "appears to be to promote bookings for direct-debit collections by its member bodies".
PFRA chairman Timothy Hornsby described the resolution, which has attracted 12 signatures, as "pernicious nonsense".
"When we are trying to do our best to keep fundraising properly regulated we could do without people making statements that are judgmental, critical and wrong," he said.
"It appears that some malign critic of face-to-face fundraising has nobbled these MPs."
Sanders was lobbied to table the motion by Charity Check, an organisation that analyses fundraising.