The catch - off the bowlingof Adam Milne - left both Zaman and non-striker Babar Azam stunned, while Williamson provided his usual understated celebration.
The wicket stopped what was a furious start for Pakistan, and led to the Black Caps eventually putting themselves in with a chance of victory.
Williamson also produced with the bat, hitting 37 from 34 balls in the Black Caps' 153-7, but despite his contributions, the Black Caps fell just short as Mohammad Hafeez hit the winning runs with two balls remaining.
Although Colin De Grandhomme and Tim Seifert both missed chances this morning, New Zealand's fielding has largely impressed in their return to international cricket after seven months away, and none more so than Williamson's special effort.