Pep Guardiola was condemned to a first trophyless season of his coaching career when Alexis Sanchez scored the decisive goal at Wembley on Sunday, securing a 2-1 comeback win for the Gunners over his City side.
They resume top-flight action with the battle for a top-four spot on a knife edge.
After Monaco dumped Guardiola's men out of the Champions League last month, draws with Liverpool and Arsenal and a defeat at Chelsea complicated their position as they aim to return to Europe's elite competition.
Losing to Arsenal at the national stadium after Sergio Aguero's 30th goal of the season gave them a second-half lead appears the most stinging setback of all, and Toure, a veteran of Manchester derbies over seven seasons in sky blue, knows an effective response is paramount.
"I'm just disappointed now but we have days to recover for Thursday. If we win, we are going to forget it [the Arsenal loss] but if we lose it will be more difficult," he said.
"City have been able to qualify for the Champions League for seven years now. Definitely, Thursday is so important."
In the aftermath of the Wembley reverse, Toure strongly criticised referee Craig Pawson and the match officials after Aguero had a penalty claim rejected before seeing a goal disallowed, with the linesman incorrectly ruling Leroy Sane's cross had swung out of play before reaching the Argentina striker.
The 33-year-old midfielder acknowledged he was wary of FA action, such was his anger and sense of injustice, and welcomed the forthcoming trial of video assistant referees in next season's competition.
"When you lose in a fair way… there have been a couple of games we have been losing, like against Monaco where Monaco were deserved winners," he said.
"But this was quite strange and disappointing as well. It is going to be difficult to forget this game because I am very, very angry.
"I don't know how to express myself because if I say something wrong the FA is going to bring a big charge. I have to be careful.
"Football is like this — you win, you lose, but sometimes it is difficult when you think it is unfair.
"When the referee makes mistakes you respect them. They work hard and it's not easy for them sometimes.
"Next season they are going to put in cameras [technology] and they have to. [We need] a couple of spots where they put the video to tell the referees if it's a penalty or a goal.
"It is better because that is fair. When it is a goal and after you look at it — the referee said no, how can you forget that? What can we do?"
Toure added: "Did you think Pep Guardiola accepted to lose the game? If the referee decides against us, what are we to do?
"I think the referee has to come now and give their point of view as well. It's too easy for them."