Calafeteanu had his first game for Romania, in 20 November 2004, with Japan, in a 25-10 win, aged only 19.
He holds 57 caps for Romania, with 8 tries, 20 conversions, 26 penalties and 1 drop goal scored, on an aggregate of 161 points. He won the European Six National Championship Cup, Group B, in 2006. He played all the four games, three of them as a substitute, at the 2007 Rugby World Cup finals, where he scored a conversion in the 14-10 win over Portugal. He was called for the 2011 Rugby World Cup, playing in three games but without scoring.