Wenger has endured a miserable campaign and frustrated supporters have turned on the Gunners boss and called for him to resign.
The Frenchman has been offered a new two-year contract to prolong his 21-year reign and reports suggest he will eventually sign it.
"When he goes back to winning the fans will be happy again. I promise you, 100 percent," Guardiola said ahead of Sunday's clash at Arsenal.
"The Premier League is not easy to win but I'm pretty sure the fans respect a lot what Arsene Wenger has done and is doing.
"People should understand how difficult football is today, all the teams are more prepared."
A latest poll reflects how much work Wenger has to do to regain the support of Arsenal fans.
Some 78 percent of the Arsenal Supporters Trust want Wenger to go when his current deal expires at the end of the season.
Arsenal are languishing in sixth place in the league, six points outside the top four.
Although City could add to Wenger's woes, Guardiola feels his counterpart will eventually turn the tide back in his favour.
Earlier this season Guardiola described Wenger as the "commander-in-chief" and he is confident the Frenchman's reputation has not dwindled within football.
"I think a manager like Arsene, who has had a lot of years in one team, is so important," Guardiola said.
"Managers lose games. He's there a long time because he's good. If not, it cannot happen," he added.
Wenger is said to have decided on his future but has not yet made it public and Guardiola added: "When the bosses decide, or Arsene decides, to stay and keep going he believes it is the best solution and the best for Arsenal.
"I'm not here to judge what they have to do and what is going to happen."
Nevertheless, the City boss will be out to pile more pressure on Wenger this weekend, although he is wary of a backlash from the Gunners.
"When you lose a lot of games it is a dangerous moment. I would prefer to take Arsenal after a lot of wins," he said.
"Everybody knows them – good quality in the middle, good quality in the sides with Alexis (Sanchez) going inside, runs in behind with (Theo) Walcott, (Alex) Oxlade-Chamberlain. Good quality. Arsenal is a top team."
Guardiola will be without long-term casualties Ilkay Gundogan and Gabriel Jesus but expects Kevin De Bruyne and Pablo Zabaleta to be involved.
"They are not top, perfect (fitness) but yes," he said when asked if De Bruyne and Zabaleta would feature.
As a further boost, Jesus is expected to return to the squad before the end of the season.
"The crutches are gone. He has started to walk and hopefully he can come back to the pitches and start to run and make some exercises," he said.
"Hopefully he can help us in the last games of the season and come back for us in the pre-season."