Manager Pellegrini admitted he must trim his squad before adding any further recruits, as City fight to comply with Financial Fair Play constraints.
Porto capture Eliaquim Mangala could be City's final summer signing unless the club can offload Sinclair and Guidetti, Pellegrini conceded.
"It's not finished, until the last day we can do different things," said Pellegrini at the Premier League launch.
"But if you ask me at this moment if I am happy with the squad, yes I am very happy with my squad.
"We had a lot of problems also with Financial Fair Play with the restriction of the amount of players we can put in our squad.
"So maybe I don't think that we are going to sign another player because we cannot do it.
"We have maybe too many players in the squad at this moment, players that need to play, that's very important, especially for young players.
"John Guidetti or maybe Scott Sinclair, they may need to play in a different team, so we'll see from now until the end of the transfer window what happens with our squad.
"But at this moment, yes we have too many players."
Pellegrini has added Bacary Sagna, Fernando, Willy Caballero, Frank Lampard and Bruno Zuculini to the champions' squad, along with Mangala this summer.
City expect to stay within the £49million spending limit imposed by UEFA for last term's FFP breaches, while Pellegrini is also mindful of sticking to the reduced 21-man squad cap.
Feyenoord are understood to be keen on completing a permanent deal for 22-year-old Sweden forward Guidetti, who enjoyed a loan stint with the Dutch club in 2011-12.
Sinclair joined Manchester City from Swansea in 2012, but has made just three starts in his two years at the Etihad Stadium.
The 25-year-old admitted after Sunday's 3-0 Community Shield defeat to Arsenal that he would seek a move if he cannot secure regular first-team football.
Refusing to prioritise the Champions League this term, Pellegrini said City cannot use FFP constraints as an excuse.
"It's easy to give excuses, but I don't like to do that," he said.
"I'll always field the strongest team and we want to win every time we play, and in every competition.
"You don't have five or six teams in any other major league where any one of them can win the title.
"So the Premier League is still the most important league, and it's important for us also."
City start the defence of their Premier League title by facing Newcastle at St James' Park on Sunday.
Pellegrini admitted he is yet to rule on whether to restore Joe Hart to his line-up after omitting the England goalkeeper from the Community Shield starting team.
Argentinian keeper Caballero made his club debut in the Arsenal defeat at Wembley, after his summer move from Malaga.
The City manager defended his rotation policy, claiming he has his players' best interest in mind rather than sheer ruthlessness.
"The best way to have high performance is to have two competitive players in each position," said Pellegrini.
"Nobody must be afraid of that: Joe Hart had a very good second part of the season last year.
"He's the best goalkeeper in England, but of course when he didn't play well last year we played (Costel) Pantilimon.
"It's impossible for a player to play 60 games in a year, to play 18 games during December and January as we did last season.
"It is sure that that player would be injured if that happened, so that's why it's so important to have two quality players in each position.
"I always decide the best team for each game, this week the same, and on Monday we will review Newcastle and start that process again."
Source : PA
Source: PA