Unfortunately, if the vehicles are registered, insured, inspected, and plated, and the parking place is a legal place, there is little that can be done. I have researched the area where you are, looking for what the problem is, and it is multi-folded. It is one of the oldest parts of the city, never designed for cars, that is the first problem. The city has done what it can, by making streets one way, allowing for more parking, but there is at least one business that has lots of patron, and there is a meetup group that also has a weekly activity in that area that brings in lots of cars. What the city should do is what they do for strip clubs, they should create a zone of exclusion, making areas of the city that prohibit any commercial establishments, and a parking permit / parking meter system would also be a real good idea.