Amid the coronavirus pandemic, officials are reportedly hoping the Champions League can return in August.
Despite City's good position, Silva is wary of Madrid, who have won three of the past four Champions League titles.
"You can't write any team off, far less Madrid who have won 13 European Cups," the midfielder told AS.
"No one else has the experience Madrid's players have in this competition, so we can't think we've already beaten them."
Silva added: "It's all very open. When you play a side like Madrid nothing is ever certain. We've seen a lot of ties in the last few years get turned around. Look at Barca last year, beating Liverpool 3-0 and then losing 4-0. You never know.
"It's a good result and we're in a great position to go through to the quarter-finals. It's a tough match and we'll need to play well and maintain our concentration."
Having won the past two Premier League titles amid numerous other domestic honours, City are eyeing a first Champions League crown.
Silva said Pep Guardiola's men were eager to claim the Champions League for the first time.
"In the last three years we've won everything in England, last season we won all four English titles, this year we've won the Super Cup and the League Cup, we're still in the FA Cup and we want to win that," he said.
"But the Champions League is the title the club, the players and Pep in England want to win. We know it's a tough tournament, but we'll fight for it."