Atletico, who are all but out of the LaLiga title race in fourth place a full 17 points behind leaders Real Madrid, have won only three of their last eight games in all competitions.
They needed a penalty shootout to edge past last year's finalists Inter Milan and reach the quarters this year after their last-16 clash ended 2-2 on aggregate.
"We just need to go out there and show what it takes to stay in this competition," Simeone told a press conference on Tuesday.
"Dortmund is probably the team who plays with the most intensity among those who qualified for the quarter-finals. We need to play an important game and we need our people to be pushing us as always."
Separately, top government officials said Spain will step up security ahead of the two Champions League quarter-finals being played in Madrid, citing threats from the Islamic State.
Atletico face a Dortmund side who came top in the so-called group of death with PSG, Milan and Newcastle, and without the perceived advantage of playing the second leg at home. They have struggled on the road but performed better at the Metropolitano stadium.
They have lost only two home matches in all competitions so far this season, handing local rivals Real Madrid their only two losses of the campaign roared on by a raucous crowd and by an in-form Antoine Griezmann who was having one of the best seasons of his career until he sustained an ankle injury in the first leg against Inter in February.
Griezmann missed four consecutive league games and played through the pain in the second leg a month later, before also missing international duty with France so he could make a full recovery and work his way back for the final stretch of the season.
"We need the best Griezmann, there's no doubt," Simeone said. "In the last few games he was injured. It's difficult to prove anything without playing.
"We have a very important week ahead of us, the group knows how important it is for everyone to be well, because we are going to need them all."
