It is often the fear and misunderstanding of dog owners that they transfer to their dogs, which leads to critical situations. Typical situation: the tiny pinscher or yorkshire that is taken up (often with one hand) because the owner fears "big, aggressive dogs". (This is totally silly btw, because if a dog the size of a labrador, say, really wants to get the small one, he'll get him, because such dogs can jump 5 feet from standing without much effort. They will just tear you down, before you ever notice, you can hold your tiny dog as high as you want - you simply can't protect him that way. So better see to it that your dog is behaving orderly - for example, does not bark at bigger ones. You can easily teach him by going away as soon as he starts to bark - this will be a sign for him that he will have to fight on its own, and he'll soon realize that it is better not to, and will follow you.)
Also, be aware that normal dogs play can appear quite violent, when in reality it is just fun to the dogs. Serious fights are seldom among good socialized dogs. Bullying happens, of course, but even then it is not correct to apply human ethics here. (Of course, if your dog can't deal with it, and you see that it doesn't want to go there, just don't go there.)
As for aggression: we don't need to prevent aggression in all cases. For example, a dog may defend its toy very aggressivly, and the other dog will know by that that he may not take it. This is a problem only if the other dog thinks it is his toy. But aggression amon dogs does not mean I will fight you until you're dead. To the contrary, this would be a sign of a psychotic dog (hopefully a rare case in your country, and usually the fact that their owners bring them to a dog park means it is not), i.e. one that does not belong in a dog park.
All in all, be sure to socialize your dog early. From the first week on, see to it, that it comes in contact with other dogs as often as possible, ideally in a puppy play group or something. The dog knows then how to behave in the presence of other dogs, and things will be good.