Beat Mexico's Tigres 1-0 to win their sixth title.
City completed the treble of Champions League, Premier League and FA Cup titles, matching Manchester United's feat in 1999 and drawing comparisons with Guardiola's 2008-09 Barcelona team.
Holders Bayern Munich beat Bayer Leverkusen 5-3 on penalties after a 0-0 draw to move into the German Cup semi-final and stay on course for a treble of titles on Wednesday.
Borussia Dortmund bounced back after slumping to their fourth straight Bundesliga defeat against Hanover 96 at the weekend, cruising past second tier St Pauli 3-0 on Tuesday to reach the German Cup third round.
Fourth division club Carl Zeiss Jena stunned Hamburg SV 3-2 in the German Cup on Sunday, taking the scalp of the Bundesliga's former European champions to cause the biggest sensation of the competition's first round.
"We are pleased with the win, the many chances and the 70,000-plus spectators."
Holders Bayern Munich crushed Hanover 96 4-1 with two goals from Thomas Mueller to reach the German Cup round of 16 On Wednesday.
Unstoppable Bayern Munich scored three goals in the opening 34 minutes with Thomas Mueller grabbing two as they eased past holders VfL Wolfsburg 3-1 away on Tuesday and reached the German Cup third round.
Manchester United beat AC Milan 5-4 on penalties after their International Champions Cup match in Cardiff's Millennium Stadium ended 2-2 in regulation time on Saturday.
Holders Bayern Munich eased into the German Cup third round with a comfortable 3-1 win at Hamburg SV on Wednesday to continue their unbeaten domestic run as they prepare for Saturday's league clash against Borussia Dortmund.
Bundesliga leaders Bayern Munich face Borussia Dortmund on Saturday with relations between the German heavyweights seemingly at an all-time low.
Pep Guardiola's appointment at the high-flying Premier League club is certainly ill-timed, argues Bikash Mohapatra.