As recently as last weekend, news reports were suggesting former Barcelona boss Guardiola was set to take over at the Etihad Stadium this summer.
Such speculation was fuelled partly by the appointment of former Barca executives Ferran Soriano and Txiki Begiristain to senior roles with the Premier League champions.
This week the Spaniard agreed to end his year-long sabbatical from the game to become Bayern Munich manager for next season, but Mancini says he was never worried about being replaced.
"I didn't have any problem for this - I understand the newspapers should write that every manager wants to take this place because it is a good place," said the Italian.
"But I think we work very well here, I have a five-year contract and I think this is possible for five years."
Mancini, 48, who guided City to their first top-flight league title in 44 years last season, is contracted to the club until 2017.
However, he has come under pressure following the club's elimination from the UEFA Champions League at the group stage and patches of inconsistent league form that sees them trail leaders Manchester United by seven points.