“It’s so difficult to win it,” Guardiola told BT Sport after the nervy 1-0 win.
“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 has now won the trophy three times 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,” added Guardiola.
“We’re going to celebrate in the hotel with family and friends. Monday the parade is in Manchester. With this competition, the treble is so difficult.”
City had suffered several near-misses in the Champions League since being taken over by their Abu Dhabi backers in 2008, including a defeat by Chelsea in the final two years ago.