I agree that the best way to deal with this is to make your dog really good in these situations..how you react will also greatly effect how your dog behaves....If you stay happy and casual, your dog is more likely to be.
Get you young dog to focus on you and reward....And give the puppy plenty of opportunity to meet lots of friendly dogs, this should have started at 8 weeks as 8-16 weeks is just the best time. But now is better then never
having gone the whole way with a very Dog aggressive dog, I gave up trying to keep other dogs away from her, so i keep her on lead and I have taught her to handle it.....very heavy on the rewards and also some desensitising and counter conditioning.....The one thing I changed in my counter conditioning was that all Trainers use "leave it", which sounds very severe and i am sure put up my blood pressure. I now use the word "puppy", even if it is a huge Irish Wolfhound. LOL.......And you can only say that word happy, so it has a chill effect. People actually say to me that their dog is not a puppy LOL, how little do they know.
When I say puppy and my dog looks at me, I give calming signals to her...it makes everything less tense. After that we meet and greet. She now tolerates most dogs, except Dog aggressive dogs, she will just have a go at them given half a chance..it is only my control over her that stops that. Just recently we did have a dog that attacked her, whilst she was on lead, he cam out of nowhere..well she had him down and out in a moment. She might be a newfie, but she is after all a mastiff. She just spat him out when I intervened and the dog ran off.
It now works as the perfect word for a situation, sounds friendly and your dog has learned the meaning of it