The association says it never conducts door-to-door solicitation and the phoney salespeople do not represent it in any way.
It says the fraudulent solicitors appear to be seeking donations and also claim to be selling "memberships" on behalf of the CMHA.
The association says the fraudsters are reportedly wearing "official-looking clothing" and are carrying a wireless debit machine as they ask people to sign up for monthly deductions.
The CMHA says no one should give the phoney solicitors their financial information.
Anyone who gets a visit from the fraudsters is being asked to turn them away and report the incident to local police.