Messi reportedly handed in a transfer request earlier this week and a reunion with Pep Guardiola could be on the cards.
It had been speculated that City were prepared to offer Siva, Jesus and defender Eric Garcia plus cash to land the 33-year-old.
However, SunSport have revealed Silva and Jesus join Mahrez on a list of players City will deem irreplaceable this summer.
Guardiola's side came second in the Premier League last season and a whopping 18 points behind winners Liverpool.
The Spaniard sees Jesus, Mahrez and Silva as a strong "core" of players to build around as they look to challenge at the top again.
19-year-old Garcia is one player who could be used as could fellow defender Angelino.
Garcia's contract is up in 2021 and was linked with a move to Barcelona prior to Messi's transfer bombshell.
Following an unproductive first meeting with new boss Ronald Koeman that reportedly left him feeling "disrespected", Messi wants to end his time at Barca after nearly two decades.
City have emerged as the front runners to seal his signature and Guardiola is reportedly in Barcelona right now to negotiate a transfer.
He had dinner at a family restaurant on Monday but reports suggest the trip to Spain was more than just a holiday.
Restaurant Kao Dimsum posted a photo of Guardiola on social media with the eatery in the suburbs of the Catalan city.
:round_pushpin: Pep Guardiola in Barcelona this evening. [via IG] pic.twitter.com/oZDpp8KEbw
- Man City Xtra (@City_Xtra) August 28, 2020
A non-essential visit seems unlikely with work to be done to prepare for the new season.
One player who could step up should Messi leave Barca is Antoine Griezmann.
According to L'Equipe, Griezmann has held positive discussions with Koeman and looks set to be given a run in his preferred central role.
The Frenchman arrived from Atletico Madrid in a £107 million deal last summer but has had a tough start to life at the Camp Nou.
Griezmann scored 15 goals in 48 appearances last season but regularly played out of position under both Ernesto Valverde and Quique Setien to accommodate Luis Suarez and Messi.
Koeman has already expressed his desire to play the World Cup winner in a central role, rather than out wide.
"With all my respect, Griezmann must play in his position," he told NOS.
"It is not an extreme. It is not. You have to play in your role. This is where the most important part of a coach comes in, knowing your players well and getting the most out of them."
Featured Image Credit: PA Images
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