It's not possible to prevent users from adding pictures of your business, there is no such functionality, Google encourage people to post pictures of the businesses they patronize.

This question came to our attention from a the Google Community boards. A business received continuous uploads of images that were of a competitor or not at all relevant to the business. The business owner followed the correct protocol of requesting that the images be removed. Eventually they were removed by Google, but soon after new images were posted by different accounts.

Here is the thread: https://support.google.com/business/thread/3257310?hl=en

If you are repeatedly attacked by spam images, the best practice is to continue to request removal but also post in the community forum with the full details. Google might be able to provide some individual support.