Speaking to reporters, Child said he took the decision because he felt he could not give his best under such heightened security environment."
He said, "It's not an ideal environment to be trying to play your best hockey and to be performing for your country."
"I think that was the major issue that swayed me when I made up my mind. It was extremely tough, probably the toughest decision I've had to make in my life," he said.
Last week, al Qaeda issued a threat for competitors to avoid the World Cup, the Indian Premier League cricket competition and the Commonwealth Games.
New Zealand coach Shane McLeod admitted that security fears have made it difficult for his players to focus on the game.
"Just having a threat hanging in the background take its toll and I think, performance-wise, it has affect us," McLeod said.
McLeod added that Black Sticks would participate in the World Cup as they have received positive feedback on security from various agencies.