The Gunners are five points away from a top-four finish after an indifferent run of Premier League form in 2013.
Giroud thinks that his side must use their morale-boosting victory at Bayern Munich as a catalyst to take all three points at the Liberty Stadium.
He told the club's official website: "When you play a few games in a week, the [final one] is always difficult for the legs.
"Sometimes you win the last one with mental strength. We have a big squad and we all want to win in Swansea. We need a strong mentality and the legs will run. Swansea play great football for a team who played in the Championship two years ago. They are a team with a lot of good players like Michu, but not only him.
"This game will be really important for us. We need the win and we need to continue our good game against Munich and our good form. There are 30 points for us to take still, so we need to trust and believe in ourselves."
Arsene Wenger's side are seven points behind local rivals Tottenham Hotspur with 10 league games left to play.