And a slow start to the game from both teams with few clear-cut chances followed.
The visitors had the ball in the back of the net after 36 minutes but Gabriel Jesus' volley was ruled out for offside.
City failed to register a shot on target in the first half for the first time in 21 matches in all competitions this season.
City started brightly after the break and went ahead on 57 minutes when Aguero pounced on Benjamin Mendy's cross and hammered the ball into the top corner.
Torres doubled their lead less than two minutes later with a curling effort from the edge of the area.
Raheem Sterling almost grabbed a third after the hour mark but his strike struck the foot of the post.
The England forward had another chance late on but curled his shot just wide as City held on to a convincing win. The defeat sees Palace remain 13th in league table.
"I'm so incredibly satisfied," Guardiola told BBC after the game. "After the Champions League it's always difficult. We made many changes. The players were sad because they wanted to play, but they did what they had to do.
"For the quality of players we had on the pitch, we should have attacked the way we did in the second half. We are one step closer -- one more game and we will be champions."
When asked if he would watch the game between United and Liverpool, Guardiola replied: "Tomorrow I will take a look. It's in our hands -- four games, one victory and we will be champions. I'm really impressed by the way we've done this Premier League. We are close."