The 33-year-old Argentina striker underwent heart tests after leaving the field, holding his chest, during Barcelona's match against Alaves in the Spanish league on October 30
Barcelona was held by relegation-threatened Alaves 1-1 on Saturday at home for its third consecutive setback.
The match between Barcelona and Alaves ended in a 1-1 draw on Saturday. Barcelona is at the ninth spot in points table with 16 points from 11 games.
City's bid to land England captain Harry Kane failed in the transfer window, with Tottenham chairman Daniel Levy not willing to let his prized forward go.
The 33-year-old Aguero was signed in July as a free agent from Manchester City, where he had many injury problems in his 10 seasons at the club.
FC Barcelona coach Ronald Koeman has said he hopes we can have an agreement for more years with club icon Lionel Messi.
Defender Juan Foyth and striker Lucas Ocampos are the most notable absentees from the 28-player squad, despite featuring regularly since Lionel Scaloni became head coach in 2018.
Spanish club FC Barcelona and Sergio Aguero on Monday reached an agreement for the player to join the club from July 1 when his contract with Manchester City expires.
However he is still not sure that Messi will be his teammate next season as the club captain is yet to sign an extension to his current contract which expires next month.
Barcelona have signed Argentina forward Sergio Aguero on a deal until 2023, the Catalan giants announced on Monday.
Aguero's final season at City has been blighted by injuries but he showed against Everton how lethal he still is, scoring twice after coming off the bench with 25 minutes remaining.
Aguero played his final game for Manchester City at the Etihad Stadium on Sunday and he ended up scoring two goals after coming in as a substitute.
Guardiola has also confirmed that Aguero is fit for Manchester City's last Premier League clash against Everton on Sunday.
Guardiola was back on the touchline in the Welsh capital and the champions were back in the old routine after their shock midweek defeat at home by Lyon in the Champions League.
Champions City edged ahead of Chelsea, who travel to West Ham on Sunday, into second, two points behind the leaders, as they bounced back from a shock Champions League defeat to Lyon.