Direct Opposites:
* Repel: To push away or deter.
* Discourage: To make someone less likely to do something.
* Dismiss: To send away or reject.
Less Direct, but Related:
* Ignore: To pay no attention to.
* Reject: To refuse to accept.
* Avoid: To stay away from.
* Repulse: To cause someone to feel disgust or aversion.
The best antonym will depend on the specific context in which "beckon" is used.