Gervinho's 88th-minute winner handed Roma a 3-2 advantage in what was an entertaining first leg at the Stadio Olimpico last week.
Despite having the upper hand going into the second leg, Garcia will urge his side to be positive and not simply hold on to what they have.
"As usual, we will play to win," he said.
"We have two high-level teams, we've seen that in the league and in the cup, (but) we play to win, then we'll see how the game goes, although it is better to win.
"This is football, in other sports if a team dominates then wins, in football if you defend the whole game you can win, we'll play to score goals, they are strong, but they can concede goals and we have seen it."
A place and four points separates the sides in Serie A, with Roma having beaten Napoli already in the Italian top flight this season.
However, despite their similarly impressive league campaigns, Garcia claims league form will not affect who reaches the final, where either Udinese or Fiorentina will be waiting.
"It's a round of the Italian Cup and has nothing to do with the league, it is a specific game, there and back, the best of two teams going into the final," he added.
"For now we are in the lead, but we will not wait, we will play our game although it will be difficult to do so. This qualification does not change anything about the league.
"We will discuss on Thursday the league."
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