The City hero has only featured eight times in all competitions this term, but did net his first goal in over 18 months during the Champions League chasers' 3-0 win over Southampton on Saturday.
Guardiola praised his captain, Vincent Kompany, who has missed most of the season through injury but headed in from a corner to score that opening goal, his first since August 2015.
Vincent Kompany, Leroy Sane and Sergio Aguero were all on the scoresheet for City as they comfortably swept aside Southampton at St Marys.
Jack Stephens prevented City from doubling their lead when he blocked Silva's 65th-minute follow up attempt after Forster pushed Kevin De Bruyne's cross back into the line of fire.
The win lifted City above Liverpool, who play West Bromwich Albion on Sunday, into third. I scored in front of the away fans and for me it was a great feeling.
Guardiola described his performance in last week's victory over Hull as "unbelieveable" and the Spaniard has now explained why he has been so impressed.
Amid speculation City boss Pep Guardiola had lost patience with the 31-year-old's fitness problems and was willing to sell him, Kompany picked a timely moment to show his class. "He's a real defender, hopefully he can be fit until the end of the season because he's an important player for us".
"Manchester United have a game [Sunday] and another game in hand and still have to come to the Etihad", Guardiola added.
Despite spending heavily in recent seasons, City's title aspirations have been hampered by an inability to build a consistent, reliable central defensive partnership in Kompany's absence.
"This result is so important for our qualification for the Champions League", said Guardiola, whose side host neighbours United in their next league game. We may decide it on whether the opponent presses high or not, or based on how they attack'.
This was a potentially tricky assignment ahead of a crunch week for City, with an FA Cup semi-final against Arsenal next weekend followed by a midweek Manchester derby.
Manchester City have only lost one of their last 10 league matches, winning five and drawing four.