MKLocalSearchRequest only accepts naturalLanguageQuery and region as parameters, so can you "perform a search that only returns addresses?"- No.
However, it's very easy to filter the list after the request has finished. If you'd like to filter out businesses from the list a simple NSPredicate does the job.
NSPredicate *noBusiness = [NSPredicate predicateWithFormat:@"business.uID == 0"];
NSMutableArray *itemsWithoutBusinesses = [response.mapItems mutableCopy];
[itemsWithoutBusinesses filterUsingPredicate:noBusiness];