Gervinho's 88th-minute winner handed the Giallorossi 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 at the Stadio San Paolo, 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 told reporters. "We have two high-level teams, we've seen that in the league and in the cup, but we will 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 they win. In football you can defend the whole game and win, but we'll play to score goals. They are strong, but they can concede goals and we have seen it."
Four points separate the sides in Serie A, with Roma in second and Rafa Benitez's men in third, but Garcia thinks league form will not affect who reaches the final.
"It's a round of the Coppa Italia and has nothing to do with the league, it is a specific game, home and away, the best of two teams going into the final," the former Lille boss 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."
The winner of the semi-final will face either Udinese or Fiorentina in the showpiece match.