how to train your dog to not be rough towards other dogs?

It STARTS with dog socialization and with obedience training classes.

How old is the dog.

How much socialisation with other dogs has he/she had?

What breed is it and what gender.

WHY does it actually NEED to socialise with other dogs?

In what way is the dog "rough"?

What is it`s basic temperament like?

Without more info it`s impossible to give you any positive advice.

When young feed them together really close. One will become aggresive but you call him off. Once they give ground for food it becomes much easier for toys, bed, attention , treats etc.

If one is male and the other is female....they had better be fixed.