The Argentina international penned an extension at the Camp Nou on November 25, much to the relief of a lot of Barcelona supporters. Had he not signed fresh terms, clubs outside of La Liga would have been able to approach Messi with a deal from January with a view to a free transfer in the summer.
It was suggested by Marca (h/t BBC Sport) that City would have offered the 30-year-old €100 million (£88 million) as a signing-on fee to make the switch. But Guardiola was dismissive when asked about those rumours, per Jamie Jackson of the Guardian.
"Messi has signed a contract one week ago," he said. "This was never going to happen; Messi started his career there and he's going to finish it there. If he wanted to leave he wouldn't have signed the contract."
When asked directly about the report, which suggested City approached Messi prior agreeing new terms, Guardiola said, "It's not true."
As noted by Eurosport UK, the release clause in Messi's new contract means even the biggest clubs in European football will struggle to prise him away from the Blaugrana:
Eurosport UK @Eurosport_UK
€700m! Leo Messi has finally signed his new contract... and it has a buyout clause that will make even PSG think twice... https://t.co/ievITHB4tx2017-11-25 11:20:42
There have been regular links to City, especially with Guardiola taking the helm at the Etihad Stadium in 2016.
The former Barcelona midfielder was in charge of the Liga side when they enjoyed one of their best seasons, winning the treble in 2008-9 and playing some mesmerising football in the process.
Guardiola crafted a role for Messi as a false nine, and he played some of the finest football of his career.
While Guardiola moved on to new challenges, Messi has remained with Barcelona and continued to enjoy success aplenty. He is so synonymous with the club that it would be peculiar to see him don the colours of anyone else.
His role in the side now is a little different to the one fulfilled so majestically under Guardiola, as Messi roams all over the pitch. But as noted by OptaJose, he continues to be the most prolific member of the side:
3 - Barcelona top-scorers this season in all competitions: Lionel Messi 17 OWN GOALS 6 Luis Suárez 6 Rarity. https://t.co/T7Olgq4lLf2017-12-5 21:41:57
Given Messi took so long to sign his new Barcelona deal, perhaps there was a feeling a fresh challenge may benefit him.
After all, he's achieved all there is to achieve with the Blaugrana at this point in his career, and a crack at a competition such as the Premier League may provide him with some fresh impetus. However, he's adored at Barcelona, and it's clear he is settled at the club.
While the biggest names in world football will always prompt discussion, transfer rumours about Messi can be shelved for now, as he's going to be a Barca player for a long time yet.
It's tough to see any team, even one with the pulling power of City, putting together a package that would prompt a change of allegiance.