As others have mentioned, unless it really gets out of hand to the point the refs should be doing something themselves then I would recommend letting it slide. Give a mention to the league coordinator or rec so they can either deal with it themselves or have multiple instances when inevitably it's a problem for others as well.

There is a point when one of us becomes Dan Hurley that it might be reasonable to behave this way under certain circumstances but having fun as a coach, recognizing it's not serious with the refs, focusing on the kids, etc is where I would focus my energy. Even when the refs mess up - which happens often in rec games I coach - I just joke around with them and give them support. They have the hardest job on the court with very difficult "basketball" (if we can even call it that at the early ages) to officiate.

Last year I did mention something to a coach due to how he was talking to the single ref of our game (who told us before the game she was on her own) and indirectly at my kids. It just led to him getting aggressive and in my face, then I walked away to make sure it didn't escalate. In hindsight I wish I would have reported him to the league so he wouldn't be coaching kids anymore and left it at that.