In a move that is sure to make Giants fans nervous, catcher Buster Posey has committed to playing for the United States in March in the World Baseball Classic.

Posey was one of 30 major-leaguers, listed in a Major League Baseball news release Monday, who have agreed to play for various countries in the MLB-run tournament.

No other Giants were listed in the release, which noted that other players will be added. However, a source told The Chronicle that Johnny Cueto is on the Dominican Republic’s provisional roster. Also, a report surfaced last week that Brandon Crawford was on the U.S. provisional roster.

A’s left fielder Khris Davis told reporters Monday that he will play for Mexico, his mother’s native country.

Players in the WBC arrive early for spring training and leave their teams to play in the tournament.

Clubs have to grit their teeth, smile and say they are all for the WBC because it’s MLB’s baby, but managers and general managers privately dislike the idea of their players competing full bore after a short winter, particularly pitchers.

Giants fans will not be happy about Posey’s participation, especially after a season in which he dealt with back and hand issues and caught a career-high 123 games, leading to questions on fatigue.

One mitigating factor: The innings he will catch in the WBC will reduce the number he catches in the Cactus League.

Big-league managers get an opportunity to ask U.S. manager Jim Leyland to limit their players’ time on the field. Leyland, who managed four major-league teams — including the Tigers in 2012 — said at the winter meetings Monday, “Last time I saw Buster Posey, he swept us in the World Series.”

Posey said last year he was open to representing the United States in the tournament, so his participation is not a complete surprise.

The other U.S. players who have committed are starting pitchers Chris Archer of the Rays and Max Scherzer of the Nationals; infielder Nolan Arenado of the Rockies, and outfielders Adam Jones of the Orioles and Andrew McCutchen of the Pirates.

Henry Schulman is a San Francisco Chronicle staff writer.