In 13 starts with the Double-A Portland Sea Dogs, the left-hander went 2-2 with a 6.41 ERA. Pena was drafted in the sixth round of the 2011 First-Year Player Draft.
This is Pena's second suspension in two years. He was suspended for 50 games in April 2013.
Quinn Roberts is a reporter for MLB.com. Steven Petrella is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.