City’s hierarchy are confident the presence of Guardiola would make them his first choice – but their manager is adamant he wants the Argentine to remain at Barca.
Asked about a potential move for Messi, he said: “I answered this question about transfers - I am not going to speak until the end of the season.
“My wish is Messi is going to stay at Barcelona.”
Messi has cut an unsettled figure at Barca this season - including a high-profile fallout with sporting director Eric Abidal.
The 33-year-old is out of contract at the end of next season, with growing reports in Spain that he is ready to leave.
Despite that, Barca president Josep Maria Bartomeu insists the six-time Ballon d’Or player will extend his contract.
“We are negotiating with many players, but Messi has explained to us he wants to stay,” he told Movistar. “And so we’re going to enjoy him for much longer.”
Guardiola plans to rebuild his squad this summer after relinquishing the Premier League title to Liverpool.
A centre back is his top priority, with the club heavily-linked with Kalidou Koulibaly.
Guardiola was also asked about a potential move for the Napoli defender, but refused to comment.