Socialising your puppy from 8 weeks old is essential. It usually starts with a friend or neighbours dog in the garden, and then by 11weeks old the puppy is out off lead and learning to meet and greet other dogs.
At 12-14 weeks old your puppy should be enrolled in puppy classes and meeting more dogs.
The more socialised the puppy the more balanced an adult dog they will be.
Should you have an negative interaction. That's ok. Take a step back and get puppy out to find three more positive doggy experiences immediately.
Do not assume all dogs are friends. Do not assume all people and dogs like puppies. Its quite all right for dogs not to like each other.
But never stand back and say 'let them sort themselves out.' Be proactive, keep all dogs safe and interaction light, friendly and positive. If there is a dog that doesn't like your dog or vice versa, its really easy...stay away.
This poster is a great example of dog interaction.