The LA Galaxy star appeared twice as a substitute at the World Cup in South Africa, coming off the bench in the 1-1 draw against England and the 1-0 win against Algeria.
Birmingham manager Alex McLeish told BBC West Midlands: "He's been training with us this week and he's done OK, but we're not at a stage yet where we're going to make any commitment."
The Scot added on the club's official website: "He's been scoring goals in the MLS and had a good season, and he's available.
"I'm not sure of the facts, but I know it's not going to cost us and arm and a leg if we do it."McLeish is short of striking options having allowed Garry O'Connor to leave St Andrew's to join Championship club Barnsley.
He has also been without Scotland star James McFadden through injury, and has been using Nikola Zigic ad Cameron Jerome up front for most of the season.
Buddle, who plays alongside David Beckham in the MLS, scored 19 goals in 28 matches last season and helped the Galaxy reached the Western Conference final which they lost.
The successful loan of Galaxy team-mate Landon Donovan to Everton last season has awakened Premier League clubs to the availability of stars from the MLS when their domestic season has finished.