I did some searching and arrived at where I started: the only parking space requirements I knew of, and could find, in various codes were limited to Accessible Spaces (refer to ADAAG Manual:
https://www.ada.gov/2010ADAstandards_index.htm )
Most parking space size requirements I recall having seen were local ordinances in their land use ordinances and/or zoning ordinances (which are often one and the same).
If the columns intrude too far into a parking space for a car, maybe mark those spaces "Motorcycles Only" or "Golf Carts Only", or convert those spaces to another use depending on the project, such as for a residential condo building, install small storage enclosures which can be assigned to certain units or available on a first come first served basis, either all such units available to all owners, or available to owners of units stacked above each storage area to reduce misuse by owners no near the storage areas from 'trashing' those other areas.
The potential other uses would of course be limited if those spaces were needed for parking.
I've been in some parking garages which have precisely the issue you are asking about, and the apparent solution they chose was to let small cars park in those spaces (or larger cars if their owners chose to risk damage to their cars), either way, warning signs of such would be needed to give the building owners the ability to try to say 'We warned you, don't blame us for any damage'.