I believe the Tao Te Ching tells us how we should act. Not in specific situations, but in general terms. Here are a couple of passages:

In dealing with others, be gentle and kind. (Verse 8)
Courteous, like visiting guests. (Verse 15)

It seems that Lao Tzu wants us to be nice to each other. And if we give up desire, I don't think we would be able to behave otherwise. Being mean, petty, or behaving in any other un-nice way is the result of various desires - to appear superior, to dominate, to gain material goods, etc. And sometimes we're not nice because we are frustrated and angry about some desire that is not filled.
The Tao Te Ching even goes a step further, saying, Reward bitterness with care. (Verse 63) This is the "turn the other cheek" idea, but a couple hundred years before Jesus is supposed to have said it. Not only should we be nice in general, we should even be nice when we are wronged. 1