City beat the French side 5-3 at the Etihad Stadium on 21 February.
Monaco have scored 123 goals in all competitions this season and Guardiola believes it would be foolish to let them attack.
“The best way [to defend] is score goals,” he said.
“When one team scores many goals and you think about just defending, you kill yourself. The idea is to try and attack.
“We scored five goals when it’s not easy to score against them. What you have to do is go to score goals.”
Guardiola, who takes charge of his 100th game in Europe on Wednesday, has no new injury concerns for the trip to Stade Louis II.
Striker Gabriel Jesus (foot) and midfielder Ilkay Gundogan (knee) are the only senior absentees.
Captain Vincent Kompany will hope to feature for only the second time since November.