In the closing stages of Friday's quarterfinal clash, the Napoli defender crashed into the back of Neymar on the edge of the Brazil area, forcing the Barcelona ace to be stretchered off.
PHOTOS: U.S. fan reactions | Beautiful people in Brazil
Hospital tests later confirmed the 22-year-old suffered a broken vertebra and will therefore be unable to compete in the semifinal against Germany, but Zuniga maintains his challenge was not an aggressive one.
"I didn't mean to hurt him. On the pitch, you have to make tough challenges, but it was not my intention to injure him," Zuniga said after the match. "Brazil were going strong and so were we. It was a normal challenge, I just wanted to defend my country.
"I hope it's nothing too serious, he's a talent for Brazil and the world of football."
Goals from Thiago Silva and David Luiz were enough to earn the home side a 2-1 win on Friday and book a last-four clash with Germany.