Those cheers were soon silenced two minutes later when Sergio Aguero fired past Ospina after good work from Kevin De Brune and David Silva and City went in at half-time 2-1 up.
Arsenal defender Shkodran Mustafi again restored parity eight minutes after the break when he rose above Nicolas Otamendi to head Mesut Ozil's corner past keeper Willy Caballero, but both neither side could find a victor.
Arsenal now sit sixth in the Premier League and are seven points off City in fourth place.
"It will help us to rebuild confidence because the players felt that we showed some mental strength". But we have come out of such a stressful period.
It is a fractious time at the North London club over the managerial situation and it appears some fans have let their frustrations get the better of them.
Man City remains seven points ahead in fourth place, with 10 games to go for Arsenal, including one in hand over Guardiola's side.
Up until today, there have been protests surrounding the future of Arsene Wenger at both home and away Arsenal matches.
"At 1-0 down and 2-1 down, just before halftime, our fans could have turned against us", Wenger said.
"If you listen to (Manchester City manager) Pep Guardiola, he said the other day that to achieve the top four in England is a trophy because it's so hard", said the Frenchman.
Wenger is yet to announce whether he will sign a new deal at the club, with his current contract expiring at the end of the season.
Wenger is the longest serving manager now working in England's top division, having joined Arsenal in 1996.
"I'm not in politics - it's not about majority or minority", he said.
He also expressed regret that City had been denied an injury-time penalty for a handball by Nacho Monreal that the Spaniard supposedly admitted to Guardiola after the game.
On Tuesday, we got the first glimpse of Wenger Out protests at London Colney. I think what is important in football is what happens inside the pitch and inside the stadium. On the mental front it was a very strong performance, and on a technical front I think we could do better.
The scrap to stay in the Premier League was the focus of Sunday's other game.