Rodri's 68th-minute strike proved enough for City to finally get their hands on club football's biggest trophy, despite having to ride their luck as Inter missed several second-half chances.
"It's so difficult to win it. They (his players) are really good. Be patient, I said at half-time. You have to be lucky. (Goalkeeper) Ederson or they miss it, they could draw. This competition is a coin. It was written in the stars. It belongs to us," Guardiola told 'BT Sport' after the nervy 1-0 victory.
Guardiola has now won the trophy three times as a coach after his previous triumphs with Barcelona in 2009 and 2011. City's victory also clinched a treble following their Premier League and FA Cup successes this season.
"After the World Cup the team made a step forward and we were there. We're going to celebrate in the hotel with family and friends" added Guardiola.