The center back has revealed his disappointment at the display of the national side in its World Cup qualifier on Friday, in which a last-gasp goal forced a 3-3 draw with Israel.
Pepe says Portugal must learn from its mistakes after fighting back from two goals down to draw 3-3 with Israel.
Bruno Alves opened the scoring for the Seleccao, but goals from Tomer Hemed and Eden Ben Basat put the home side 3-1 in front, before Helder Postiga and Fabio Coentrao saved the day for the visitors.
"The problem was not just the defensive aspect,” Pepe told abola.pt. "We left spaces between the middle and the wings, but we must learn from mistakes so that will not happen in the next game.
"We wanted to win, we are sad, we had the conditions. The most important thing is that we are in the competition to fight."
Portugal is third in Group F -- level on points with second-place Israel but behind on goal differential -- with Pepe and his international teammates facing an uphill battle to qualify for World Cup 2014, but the 30-year-old is determined to do all that he can to achieve that goal.
"I am part of the Portuguese national team and want to be at the World Cup. We will do everything to be there - now we must learn from mistakes."