Pappa earned his first cap for the senior national team on 20 August 2008 in a 0–1 World Cup qualifying loss to the United States, appearing as a substitute. He scored his first goal for Guatemala on 15 October 2008 against Cuba. He participated at the UNCAF Nations Cup 2009 and at the 2011 Gold Cup, where he scored the second goal of a 4–0 win against Grenada.