A lawyer for Atdhe Gashi says he was forced to fight back when a group of men attacked him without provocation.
Gashi was being beaten by several people when he pulled out a small knife he used to open packages at work and slashed at 25-year-old Elliott Paulino.
The fight was captured on security cameras.
Gashi sobbed in a Manhattan courthouse after the grand jury decided he shouldn't face charges.
His lawyer, Robert Brown, says his client is a computer science student who had never been in trouble before.