Fresh from winning the Premier League title for the second time in three seasons last weekend, City are now planning their squad changes for next term.
Arsenal full-back Bacary Sagna has been strongly linked with a free transfer move to the Etihad Stadium, while Porto duo Eliaquim Mangala and Fernando are also reported to be wanted by City.
Soriano has confirmed City have already settled on their targets for the summer and has suggested there will not be a major overhaul of Manuel Pellegrini's squad.
"The planning has been done already," said Soriano in the Manchester Evening News. "We don't do this in the summer, we do this during the year.
"We know that some players will be leaving because their contracts are finishing. We have some new players coming.
"But it's fair to say that the base of our team is going to be the same.
"These players are players who are winning. Remember, we have only been working with Manuel Pellegrini for one year so we are sure next year it will be better.
"To build a team needs time. You will see some changes in the team but not massive."
Several players are also likely to leave City, with England defender Lescott definitely on his way when his contract expires.
Lescott acknowledged earlier this week that he is resigned to leaving City and Soriano has praised the former Everton centre-half's contribution.
Soriano added: "Joleon Lescott is finishing his contract and is leaving. Joleon has been a key player for us. Not only for what he did on the pitch but also his leadership and character in the team. We wish him well.
"Some players leave and some new players will come. We're not changing the base of the team."