"They were able to shut us down in some parts of the game and we struggled to respond to that pressure.
"We need to go away and make sure we put together a top performance against Malaysia to get some momentum going into the quarter finals."
It was a fast-paced opening quarter with both sides creating chances on attack but unable to put goals into the back of the net.
Belgium had the advantage in possession in the first half although the Black Sticks played very well on defence to keep out of trouble.
The hosts broke the shackles late in the third quarter when Anouk Raes put on a spin move in the circle and hit into goal between the legs of goalkeeper Sally Rutherford.
New Zealand battled to find an equaliser after the goal and had several great chances from penalty corners but Belgium's desperate defence held firm.
The Black Sticks play Malaysia in their final pool match at 2:00am on Wednesday morning (NZT), with live coverage on SKY Sport.