City announced earlier this week that striker Aguero, who has scored 257 goals for the club, will leave the Etihad Stadium when his contract expires at the end of the season.
City have been linked with Erling Haaland, Harry Kane and Kylian Mbappe but Guardiola is not sure such targets are realistic.
There is a big chance we are not going to sign any striker for next season
Guardiola said: “There is a lot of big chances that maybe we are not going to sign a striker for next season.
“We have enough players in the first team right now and we have interesting players in the academy.
“There is a big chance, with the situation in the world, the economic problems in world football, we are not going to sign any striker for next season.”
Guardiola admits the club’s decision not to renew terms with Aguero, 32, was a tough one.
He said: “We know how important a player he is in the present and was in the past. These decisions are never easy.
“Maybe we could find a new player to replace Sergio in terms of numbers but it is almost impossible to replace him in terms of what he means to this club.”
One in-form striker Premier League leaders City are set to come up against as they travel to Leicester on Saturday is their former player Kelechi Iheanacho.
The Nigerian, who left City in 2017, has scored seven goals in his last four games for Brendan Rodgers’ Foxes.
Guardiola said: “Incredible. The quality was there. He was a young player here and I think with Gabriel (Jesus) we didn’t have enough space.
“He is a fantastic person, we had a good relationship, and I’m glad to see him playing well.”
Guardiola has reported no fresh injuries ahead of his quadruple-chasing side’s trip to the King Power Stadium but not all players away on international duty have yet rejoined the squad.
He said: “There are six, seven, eight players we didn’t see. They were not allowed to come into the bubble for the test. Today we will make the training session and are going to decide the team and see how the players have come back from the international break.”