Zeus, or the gods in general, is punishing Creon's negligence in regard to proper burial rites.

In Antigone, Tiresias is a wise, blind prophet of Apollo. When he visits Creon, he is speaking for the gods. He knows that the gods are displeased, because they refuse to accept any sacrifices. Creon has broken the laws of the gods by refusing to bury Polyneices, choosing instead to leave him on the battlefield where he fell, as carrion for scavengers. When Antigone criticizes this edict, Creon gives her the harsh punishment of being sealed in a cave alive.

Tiresias informs Creon that the gods will not abide this. He warns Creon that Polyneices must be buried immediately and that Antigone must be released from the cave, or Creon will lose a son.

This is a good question, as the gods and Zeus in particular are very important within ancient Greece. 

A close examination of the play will show that Zeus is against several things. First, in line 100-105 the chorus states that the gods hates arrogance. To be more specific, the gods hate bragging tongues. 

For God hates utterly. The bray of bragging tongues; And when he beheld their smiling, Their swagger of golden helms, The frown of his thunder blasted Their first man from our walls...

This should not surprise us, as hubris is something that the gods hate in much of Greek literature. 

Second, Zeus hates the denial of burial. Creon is too arrogant to see this. His logic is that burial rites do not extend to criminals. He fails to realize that he is "criminal" by not allowing these burial rites. In connection with this, the chorus reminds Creon that the gods hate people to break divine laws. Creon capitulates only when Tiresias puts the fear of God into him. In a word, Zeus hates pride.