Manchester City has spent £200 million so far in the window and Guardiola admits it is not sustainable.
Guardiola brought in players like Ederson, Bernardo Silva, Mendy, Walker and Danilo before the season kicks off.
City were linked with signing Mbappe, but it seems they have cooled their interest.
“I think it is unsustainable,” Guardiola said. “Sooner or later it’s going to finish.
“For example, hopefully next season I will be here and we are not going to spend how we spent this season. Six players were out of contract. In the last six or seven years Manchester City didn’t buy full backs. We didn’t have full-backs and you have to buy full-backs.
“We bought three and the market is so demanding for all the teams, not just Manchester City.
“It started with Real Madrid and Ronaldo going for £80 million and then Bale for £85 million and everything went more expensive. Now with Neymar.
“But it is going to finish, it is unsustainable. In the next three or four years Manchester City will buy one, two, maybe three players. But not what happened this summer.
“We needed to do that because it was one of the oldest teams in Europe, not just the Premier League, and we needed to change it. We were not able with those players to find a solution. But the solution is not changing players every season.”