The International Federation of Football Associations (FIFA), the governing body of world soccer, yesterday dismissed bids by the United States and Canada to be host for the 1986 World Cup and announced it would consider only Mexico as a host country.

Although, in effect, this gives the World Cup to Mexico, FIFA was not expected to decide formally until May 20. In dismissing the U.S. and Canadian bids, FIFA cited an insufficient number of stadiums and traveling distances that would make a World Cup in either country impractical. All three bids will be submitted to FIFA's executive committee; only Mexico's will be studied in advance.

Colombia, which was to be the site of the 1986 Cup, withdrew its bid last fall because of a lack of financing. The 1970 Cup was in Mexico.

FIFA's decision angered and disappointed soccer officials in the United States and Canada. Neither the United States nor Canada has been the site of a World Cup, and both countries had submitted detailed proposals to FIFA after Colombia defaulted.

"I am truly outraged at the FIFA's announcement that they would only consider Mexico . . . without even making inspection tours of the U.S. and Canada," said Howard Samuels, executive director of the North American Soccer League. "To deny both countries the opportunity to present their cases in person because of the supposed distance problems between stadiums is unrealistic."

"My feeling was one of surprise and disappointment, both at the news and the manner in which it was released," said Jim Fleming, president of the Canadian Soccer Association.

"The World Cup would have given a shot in the arm for soccer in Canada," said CSA Executive Director Eric King. "If travel time or stadia were issues, they could have told us that years ago and saved us all a lot of time and money."

FIFA officials could not be reached for comment at their offices in Zurich.

A five-member FIFA delegation was to have visited all three countries in mid- or late April to review proposed stadiums (including RFK Stadium in Washington), training sites and accommodations, but apparently will visit only Mexico. The host nation receives an automatic bye into the final round of the tournament.

FIFA's decision is especially surprising since the U.S. and Canadian bids had the full support of their governments and projected large profits, something the last two Cups (in Argentina and Spain) were unable to attain. President Reagan formally endorsed the United States' 92-page proposal in a letter to FIFA March 23, and Canada's bid was backed by $50 million in support from its federal government.

"When you look at the growth of the game in America today, with its rank as the fastest-growing team participatory sport, it is shocking that FIFA would not personally examine our country and give us the chance to show them what we can do," said Samuels. He contended that Mexico, whose economy has faltered, exerted enormous political pressure to secure the Cup.

FIFA did not cite specific examples for rejecting the bids, but the approximately 3,000 miles between the east and west coasts in both countries was seen as excessive. In addition, Canada proposed using nine stadiums instead of the minimum 12, including one domed stadium (Vancouver). A World Cup game has never been played indoors.

FIFA's decision is not expected to affect the progress of Team America or the proposed Team Canada, the countries' national teams-in-training, which will compete in the NASL.