A disabled placard is not carte blanche to park anywhere you like no matter how few disabled spots are available.
If the HOA rules do not permit residents to park in the guest spaces, you can indeed be towed.
You can check to see if the lot was appropriately posted and the tow was specifically authorized, but if it was, you're out of luck.
Your placard allows you to park in disabled-marked spaces (sign, blue curb), at meters for free, at green curbs for any period of time, and to disregard the on-street residents/merchants only designation. It doesn't allow you to park in spaces restricted otherwise (including on private property).