International sport officials quickly discounted the possibility of a boycott of the tournament, which is set to take place June 8-July 8, 2018, in 11 Russian cities.
The 30-year-old Ivory Coast footballer said he was subjected to monkey chants by groups of fans from the Russian CSKA club.
CSKA retaliated by accusing Toure of a smear campaign. The boycott threat follows a series of incidents across Europe in which players of African origin and black European players have been subjected to monkey chants and other verbal attacks defined as racist.
European football's Union of European Football Associations said it was investigating the incident reported by Toure. UEFA didn't say when it would release findings of its probe.
There was no immediate comment from the Russian government over Toure's warning that players would stay away if they didn't feel confident coming to Russia for the tournaments.
UEFA can bar CSKA from using its stadium for a future game, but a CSKA statement said, "Having carefully studied the video of the game, we found no racist insults from fans of CSKA."
Toure retorted he wasn't deaf and insisted he was subjected to racist chats. The player received public support from Piara Powar, executive director of European anti-discrimination body Football Against Racism in Europe and a member of Fifa's anti-discrimination task force.
"Yaya Toure is absolutely right in raising the specter of African players or players of African heritage not going to the 2018 World Cup -- and without them there will not be a World Cup in Russia," BBC reported.
"I wouldn't blame them. In this era, players are the most powerful force and if all the players said they are not going there wouldn't be a World Cup, or if there was it would be meaningless."
Although international football officials have remained low-key on the issue, footballers and their representatives say the threat of boycott may in fact lead to positive change and tougher measures against racism in sport. Footballers accused both UEFA and FIFA of seeking to minimize the problem.
The Kick It Out anti-racism campaign expressed full support for Toure and called on UEFA to act.
The incident is a source of embarrassment for UEFA, which had declared this a Football Against Racism in Europe, or FARE, Action Week, The Guardian reported.
UEFA has said its control and disciplinary body will convene Oct. 30 to decide if CSKA should face sanctions. Under regulations brought in place at the start of the season, if CSKA's supporters are found guilty of racist behavior, the most likely punishment would be a partial closure of their ground as it would be the club's first offense, the newspaper said. A second offense leads to a full stadium closure and a fine.
The Guardian said the reported Toure incident revived doubts about Russia's suitability as host to the World Cup finals in 2018.