A Nicholas Otamendi own goal put the host in the lead before Sergio Aguero converted a penalty to equalise for Pep Guardiola's side.
"Two clear penalties. Maybe Arsene will say that is (a) penalty", the Spanish tactician said, as quoted by FourFourTwo.
The victory also sets a new club record for City who have now won in 11 consecutive away matches in all competitions.
"If you want to win the title you cannot expect easy games, so we have to live these kinds of situations and we spoke about at half-time how we are going to react in that situation", he said.
"We are not going to finish (the season) unbeaten, it is impossible".
"When you play every few days, when you see the scheduling - December, January - we go to Donetsk to play in the Champions League". We have a good moment and with the spirit we can go further.
United were the best-paid team in the world in last season's GSSS, but players with big contracts such as Wayne Rooney and Bastian Schweinsteiger have since been offloaded.
Rep. John Conyers steps down amid sexual harassment investigation
Conyers has admitted to making the payment to avoid public litigation, but has denied any sexual harassment claims. Last month, she shared her own story of being sexually assaulted by a high-level aide while she was a staffer.
Raheem Sterling's fortunate late victor gave City the three points after they recovered from the shock of falling behind to a Nicolas Otamendi own goal on the stroke of half-time.
United defender Victor Lindelof hopes his side can continue to grind out the wins while they search for their peak form.
Chelsea star Willian insists he is hoping to win many more trophies with Chelsea amid speculation he is looking to leave the Premier League champions.
The Premier League has become the first football league ever to boast an average wage for players of over £50,000-per-week, according to a new study. The match ended in a 1-1 draw. "We'll be there to help him".
"I think the penalty is more than evident".
Earlier, Arsenal scored in the dying minute to defeat Burnley 1-0 while Southampton defeated Everton 4-1.