The Barcelona star has been ruled out of the rest of the World Cup after breaking a vertebra in his back after Zuniga caught him with a high knee in the 86th-minute of Brazil’s quarter-final victory over their South American rivals.
FIFA have since confirmed they will not take retrospective action over the incident but Thiago – suspended for the semi-final against Germany – has hit out at the Napoli full-back.
"In my opinion, it was a cowardly tackle. I'm a defender and you don't do that," said Thiago.
"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."
Spanish referee Carlos Velasco Carballo did not show Zuniga a yellow card and the Confederation of Brazilian Football complained to FIFA about the challenge, with Brazil coach Luiz Felipe Scolari claiming Colombia had been "hunting" Neymar.
FIFA's disciplinary panel, which was chaired by Claudio Sulser, studied the video of the incident but they decided they were unable to consider the matter under the rules as the incident was seen by the match officials.
They therefore declined to open proceedings against Zuniga, who apologised to Neymar on Saturday.
A FIFA statement read: "The chairman of the FIFA disciplinary committee deeply regrets the incident and the serious consequences on Neymar's health.
"No retrospective action can be taken... since the incident involving the Colombian player Juan Camilo Zuniga Mosquera did not escape the match officials' attention.
"The conditions by which the FIFA disciplinary committee can intervene in any incident have to be considered independently of the consequences of that incident, such as an unfortunate injury suffered by a player.
"We wish Neymar a prompt and complete recovery as we wish the same for all players who have sadly been ruled out of the World Cup through injury."
Watch Neymar and Thiago Silva compete in next season's Champions League on Sky Sports 5