The pair join striker Gabriel Jesus and defender John Stones who will miss Wednesday's Premier League clash against West Ham United although they are progressing well from groin injuries.
"I don't know how long they (Fernandinho and Laporte) will be out... maybe in the Swansea game or after the international break. In the next weeks, they will be out but I think John and Gabriel will be back soon," Guardiola told reporters.
Full back Benjamin Mendy has returned to training after a knee injury and could face West Ham.
Wednesday's game marks the first time West Ham boss Manuel Pellegrini, who guided City to a league title and a League Cup triumph in 2014, returns to the Etihad Stadium, and Guardiola hailed the Chilean's contributions to the club.
"He did an incredible job. The league he won, the way he played. It was a good team," the Spaniard added.
"I have a lot of respect for the people who played and managed here, especially Manuel. He's an excellent person, polite and shows respect."
City are second in the league table with 65 points from 27 matches, one point behind leaders Liverpool, and Guardiola said the champions had to show their winning mentality to retain the title.
"In the last two months the mentality makes the difference," Guardiola added.
"We have a good squad, a good second team. I want to see the desire that we want to win the title. I don't care about the way we play. I want the smell that we can win.
"I don't want excuses about tiredness, fixtures, schedules, or how many games. When you have the illusion to fight until the end, to retain the title, the power and the energy to give you that, it's higher than any excuses you can find."
(Reporting by Shrivathsa Sridhar in Bengaluru; Editing by Hugh Lawson)
