Rosberg carefully managed his tyre strategy through the race, controlling his pace at the start of a stint before being able to push later on.
That tactic worked because overtaking is so difficult in Monaco, but Mercedes will not be able to repeat that approach at other venues where passing is easier.
Amidst a backdrop of controversy regarding Mercedes' recent secret tyre test with Pirelli, team principal Ross Brawn said the victory in Monaco in no way showed his team had mastered the F1 W04's tyre issues.
When asked by AUTOSPORT about the situation, Brawn said: "It is a constant challenge and I wouldn't pretend that we are on top of it.
"This is a race where you were able to manage the situation without anyone getting past you.
"The purpose of the slow start to the race was to manage the situation. We cannot do that at other tracks, so I think we still have a long way to go."
Brawn said that there was little doubt Rosberg's team-mate Lewis Hamilton would have taken a top three finish if he had not been so slow in to the pits during the first safety car period.
"Obviously we had a bit of a mix-up with Lewis that didn't quite work out under the safety car," he said.
"I think that was an unfortunate aspect of him being new to the team and us being new to him. So that didn't quite run as planned.
"But he was in very good shape today as well and, if he hadn't have had that, he certainly would have been on the podium."
Brawn is upbeat, however, that that the team can look forward to a similarly strong showing at the next race in Canada.
"This win is a great boost," he said. "I do wonder what is worse: qualifying on pole and not delivering, or not qualifying on pole and finishing where you qualified. I am not sure.
"We have got another circuit coming up where we can be reasonably optimistic, so it was very pleasing."