Bale was included in Stuart Pearce's Great Britain squad for the Olympics but was withdrawn due to injury.
However, the ex-Saint played for Spurs last night and scored in a pre-season friendly against Los Angeles Galaxy in California.
The FA and British Olympic Association have not commented on Bale's appearance, but Blatter said if there was an official complaint to FIFA then the 23-year-old could be banned for playing again for Spurs - even in friendlies - until August 12.
The world governing body would have to judge that the club had not released him - Spurs would argue Bale only returned to fitness this week. Asked about Bale, Blatter said: ''The principle is that if a club does not release a player then this association can come to FIFA and we will then ban this player during the duration of the Olympics.
''So far nobody came to FIFA to say we should, but it is a possibility we could ban these players if they are not at the disposal of the national team.
''They (the association) complain and then we say let this player go or he cannot play for the club.
''FIFA's position has never been so clear than it is now for the Olympics 2012 and 2016.''
Blatter admitted that some countries such as Switzerland had not insisted on clubs releasing players but that all were entitled to.