Nasri has warned that City have no qualms about facing either of Spain's big guns when the draw is made at lunchtime.
After finishing second behind defending champions Bayern Munich in their group, City will most likely face a difficult draw.
In addition to either Madrid or Barca, Manuel Pellegrini's men could line up against last year's beaten finalists Borussia Dortmund, French champions Paris St Germain or joint La Liga leaders Atletico Madrid.
Former Arsenal midfielder Nasri claims none of those names should be feared, saying: "No, I am not worried. They will not be happy to play Manchester City.
"But if I have to pick one one team I go for Paris, Atletico Madrid or Borussia Dortmund. I don't want to play Real Madrid or Barcelona.
"But everyone looks at these kind of games (beating Arsenal 6-3), and what we did midweek (against Bayern Munich), and they are worried about those kind of teams."
England's other group winners Arsenal face similar prospects to City, though cannot be drawn against Dortmund after sharing the same group.
The north Londoners could face Bayern, PSG, Barcelona or either of the Madrid clubs.
On paper group winners Manchester United and Chelsea should gain a more favourable draw.
But either side could face AC Milan, the last Italian side left in the competition.
United's other four potential opponents are Galatasary, Olympiacos, Schalke and Zenit St Petersburg.
Chelsea cannot face Schalke after being drawn together in Group E, so they could take on Leverkusen, in the only change from the permutations facing United.
Tottenham and Swansea will also learn their Europa League fate on Monday, for both the round of 32 and last 16.
The 12 group winners and four best third-ranked teams dropping down from the Champions League will make up one half of the draw.
In the other seeding pot will be the 12 group runners-up and the remaining third-placed Champions League sides.
The last-16 draw will be made immediately afterwards, and will be completely open.
Among Group K winners Tottenham's 14 potential opponents are big names Lazio, Ajax, Juventus and Porto; so Andre Villas-Boas' sides 100 per cent tournament record could be severely tested.
The draw could be fairly daunting for Group A runners-up Swansea, with Michael Laudrup's side able to face Napoli, Benfica, Shakhtar Donetsk and Basle dropping down from the Champions League.
Swansea could also draw the likes of Fiorentina, Sevilla and Lyon.