Zuniga's poor challenge into the back of Neymar fractured the forward's vertebra during Brazil's 2-1 quarter-final win over Colombia on Friday.
The right-back escaped without punishment during a leniently-refereed clash as the teams combined to commit 54 fouls, with Spanish official Carlos Velasco Carballo dishing out just four yellow cards.
Napoli defender Zuniga said he never meant to hurt Neymar.
"It was a normal move. I never meant to hurt a player," he said.
"I was on the field, playing for the shirt from my country, not with the intent to injure. I was just defending my shirt."
Neymar, who has scored four goals at the World Cup, has been ruled out for several weeks due to the injury.
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