Neymar fractured a vertebra in his back when he was caught by Zuniga's knee in the closing stages of Brazil's 2-1 victory over Colombia in their quarter-final on Friday, and Silva believes that the defender was keen to hurt the Barcelona forward with the tackle.
"In my opinion, it was a cowardly tackle. I'm a defender and you don't do that," Silva told reporters.
"There's no way you put a knee behind a player to get a ball in front, unless you want to cause a certain situation."
FIFA confirmed on Monday that Zuniga would face no punishment for the challenge.