PSG won the first-leg of their Champions League semifinal 1-0 thanks to Ousmane Dembele's fourth minute goal.
Arteta conceded afterwards: "Disappointed with the result. We put so much into the game. We struggled first 10-15 minutes to get momentum and dominance. Disappointed not to get a draw at least."
On PSG's early goal, he also said: "That is always the danger, credit to them. They get out of a situation that is close. We had seven players behind the ball and they were clinical, sometimes you just have to recognise the talent of the individual.
"Great timing, the margins, millimetres offside. The action of (Gabriel) Martinelli one-on-one, he has done that before. (Leandro) Trossard in a one-on-one and he (Donnarumma) makes the save. That's the margins, that's the level."
Asked if they missed Partey, Arteta insisted: "I think Declan (Rice) and Mikel (Merino) were enormous.
"He gives options and a different threat. It gives us flexibility to change the game. It's half-time and we have a big chance to be in the final."