Mancini's position as manager has come under increasing scrutiny in recent weeks with the club putting up a limp fight in defending their Premier League title - City are now 15 points behind leaders Manchester United with just nine games remaining.
Although they remain in the hunt for the FA Cup, a second successive failure in the Champions League means this campaign is likely to be viewed as a failure given the heavy investment made in the squad yet again last summer.
The arrival of former Barcelona technical director Txiki Begiristain as director of football alongside Soriano in October, raised suggestions that preparations were being made for a change in management in the summer.
However, Soriano has appeared to offer his backing for Mancini, highlighting how difficult it can be for a side to retain their title.
He has also suggested that with UEFA's Financial Fair Play regulations looming, the days of lavish spending by owner Sheikh Mansour could be at an end, with the currently-under-construction Etihad Campus a sign of things to come.
"My way of football? One year you can win with luck, but in the long-term you need planning and investments to reach the final of the Champions League," Soriano told Gazzetta Dello Sport. "Our problem is to find players stronger than the ones we have and that is not easy.
"In the last three years there have been losses of €235m (£199m), then of €118m (£199m) and now there is a 'red line' of €59m (£50m) imposed by UEFA's Financial Fair play regime.
"But we also have just invested €150m (£127m) for the infrastructure of our youth system [the Etihad Campus]. It's a fantastic project, focusing on financial sustainability."