Bayern shocked Europe by running out 7-1 victors in the Italian capital two weeks ago, and midfielder De Rossi said that result - coupled with injuries to several first-team players - meant the Serie A side had no chance of avenging that in Germany.
Pep Guardiola's formidable Bayern outift once again had too much for Roma, as goals from Franck Ribery and Mario Gotze gave them a 2-0 win and top spot in Group E.
"It wasn't easy to lose 7-1," De Rossi told Sport Mediaset. "We gave our all and took a different approach, admitting they are superior and taking counter-measures.
"We hoped it would be enough to take home a point, but at least we gave a better account of ourselves.
"[Winning] was an impossible task tonight. Let's not forget we are missing fundamental players."
Fellow Roma midfielder Radja Nainggolan added: "We are aware that Bayern are a couple of steps ahead of us.
"We tried to adapt to their style of football and generally didn't allow them many clear opportunities, so today we proved that we are a team who can play this way too.
"The important thing tonight was to send a signal to ourselves that last time was just a one-off. We showed that we are also capable of defending and counter-attacking, while we wasted a few chances.
"We are still second [in the group] and things are not that bad. We got the approach wrong [at home to Bayern], wanting to take the initiative, and conceded two early goals that made everything more complicated.
"If we play with this determination, we can do well."
Roma are second in Group E, level on points with CSKA Moscow and two above Manchester City with two fixtures remaining.
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