FIBA Europe
With the junior national teams of Greece, Antonakis played at the following tournaments: the 2008 FIBA Europe Under-16 Championship, the 2009 FIBA Europe Under-18 Championship, the 2010 FIBA Europe Under-18 Championship, the 2011 FIBA Europe Under-20 Championship, and the 2012 FIBA Europe Under-20 Championship.