Manchester City have been hit by 11 positive cases to players and staff in recent weeks and even though Aguero has tested negative, Guardiola confirmed he must isolate due to the protocols for close contacts.
"Manchester City FC can confirm that Scott Carson, Cole Palmer and one member of staff have tested positive for Covid-19," the club said in a statement.
The revelation about Mendy’s rule-breaking comes as City deals with the impact of a coronavirus outbreak at the club that led to the postponement of Monday's match at Everton and forced at least five players into self-isolation.
Premier League: Manchester City's Gabriel Jesus, Kyle Walker ruled out until New Year after contracting coronavirus
Two members of staff have also tested positive for the virus with Brazil's Jesus and England's Walker set to be sidelined until League Cup semi-final on 6 January with Manchester United due to a 10-day quarantine.
Premier League: Manchester City's Rodri believes adaptability is key as Pep Guardiola's men gear up for derby against United
Rodri also elaborated on the difference between playing in LaLiga and Premier League in terns of style of play.
Pep Guardiola's Manchester City have had a patchy start to the season but are now just three points behind leaders Tottenham after a dominant display at the Etihad.
Champions League: Bayern Munich, Manchester City cruise to last 16; Liverpool slump to home defeat against Atalanta
On a night when clubs marked news of the death of Diego Maradona by holding a minute's silence in memory of the Argentine before all Champions League games, Bayern eased to a record-extending 15th straight win in the competition.
Champions League: Pep Guardiola feels Manchester City's progress in European competition is undervalued
Manchester City are sitting pretty in Group C with maximum points from their opening two games against Porto and Marseille.
Premier League: Pep Guardiola says he’s nowhere in Marcelo Biesla's league despite massive lead in title wins
Guardiola faces Bielsa, who he credits as one of his inspirations, for the first time since 2012 when Manchester City visit Leeds in the Premier League on Saturday.
City did not disclose financial details but Benfica had already announced on Sunday that it was selling Dias to the Premier League club for €68 million ($78 million).
Manchester City owners City Football Group acquire French Ligue 2 outfit Troyes to extend global portfolio
The City Football Group will become the new majority shareholder in Troyes after buying the stake from previous owner Daniel Masoni.
UEFA Nations League: Phil Foden hails Pep Guardiola's 'massive' faith in him as he eyes England debut
City boss Guardiola has regularly lavished praise upon Foden, saying he would not sell the young star even for €500 million ($590 million).
Champions League: Manchester City have matured in tournament since previous disappointments, says Gabriel Jesus
Jesus had a standout performance in Friday's 2-1 win over 13-time European champions Real Madrid that earned a place in the quarter-finals.
De Bruyne, who has recorded 11 goals and 19 assists in the league this season, finished runner-up to Liverpool’s title winning captain Jordan Henderson in the annual FWA vote.
Pep Guardiola says Manchester City deserve apology after criticism from Mourinho, Klopp on ban verdict
Guardiola said the club’s reputation had been damaged by the furore around allegations that they broke Financial Fair Play (FFP) rules and fired back at comments from rival managers Jose Mourinho and Jurgen Klopp.
The fact that such a high-profile case ended in failure for UEFA — is a defeat for UEFA’s Club Financial Control Body.
Champions League: Manchester City can’t afford to look beyond Real Madrid return clash, says Pep Guardiola
City boss Guardiola said it was still too early to think about a possible quarter-final clash against Juventus as Real Madrid still are a dangerous side despite losing 2-1 at home in the first leg.
Premier League: Leroy Sane to leave Manchester City after turning down contract deal, reveals Pep Guardiola
Leroy Sane's contract runs out at the end of next season and reports have linked him with a move to Bayern Munich. Guardiola said he had wanted Sane to stay but the player wants to make a fresh start.
Premier League: Manchester City midfielder David Silva to stay with club till end of season, confirms Pep Guardiola
David Silva will stay at Manchester City until the end of the Premier League season, manager Pep Guardiola announced on Tuesday.
Manchester City boss Pep Guardiola has appointed his mentor and coaching inspiration Juan Manuel Lillo as his new assistant, the Premier League club said on Tuesday.