If a group of adventurers finds a unique and reasonable way to avoid a fight, let them win it without any bloodshed. 

There is no reason to force a battle if there is another way. DnD is a really good way to be creative and try different things.

For instance if a group of goblins shows up, the group might decide to pull out some treasure and convince the goblins they know where more treasure lies. Well, if they are persuasive enough, the goblins are certainly greedy enough to make it work