Wrestling's world governing body FILA has said it is "greatly astonished" by the International Olympic Committee's decision to remove it from the programme for the 2020 Games.
In a statement, the governing body vowed to fight what it called the "aberration" of the announcement, which came following a meeting of the IOC's 15-strong executive board in Lausanne.
A statement on the governing body's website read: "FILA was greatly astonished by today's recommendation of the IOC executive board not to maintain wrestling among the 25 core sports for the 2020 Olympic Games."
The statement continued: "FILA will take all necessary measures to convince the IOC executive board and IOC members of the aberration of such [a] decision against one of the founding sports of the ancient and modern Olympic Games."
Wrestling will now become one of eight sports - along with the likes of squash, karate and baseball/softball - bidding for inclusion in the 2020 Games, with a decision due at the IOC Congress in September.
IOC communications director Mark Adams said: "This is not what's wrong with wrestling, it's what's right about the other 25 core sports. This process is about looking to renew the Olympic Games and the executive board made their decision based on their experience.
"They have a collective intelligence there with representatives from many sports, national Olympic committees and international federations and they came to that decision."
News of its exclusion came as a shock to the wrestling community, with modern pentathlon and taekwondo having been considered two sports at greater risk.
Great Britain sent only one wrestler, the Ukraine-born Olga Butkevych, to London 2012 after losing all its UK Sport funding due to a lack of realistic medal chances, and she said: "I am disappointed to hear the IOC's decision. I would like to do my best for Team GB at 2016 but it is going to be a real challenge."
Great Britain has won two post-War Olympic wrestling medals, the last a bronze for light-heavyweight Noel Loban in Los Angeles in 1984. And British Wrestling chief executive Colin Nicholson said: "It has come as a big surprise. Wrestling proved very popular in London and it has a very wide appeal across the world."