The countries meet again in Buenos Aires on Saturday in their second game of the Southern Hemisphere competition after the All Blacks won 41-24 last weekend.
"Obviously, it's the All Blacks. They knew how to take advantage of our mistakes," Isgro told reporters at training.
"But we also cancelled a lot of what they had planned, but they changed their game and started to make it simpler, and we couldn't dominate them there.
"Even so, I think we were in the contest throughout the entire match. We came within a try in the second half of tying them. There were a lot of things that we worked on during the week before that we utilised well in the match, which for me is super important."
The 26-year-old, who plays his club rugby at Harlequins in London, was one of the three try scorers for Argentina in Cordoba.
"It was my first game against the All Blacks. There's something different about playing them," he said.
"The day before the Test, I remembered when I used to do the haka at home. There were sentimental aspects to playing the All Blacks, which made me really emotional.
"But once I was out there, I knew the attention the game required, and you must try to manage any emotions.
"Personally, I felt good. I'm quite self-critical. I know I must keep improving and there are things I can do much better."
Looking ahead to Saturday's game at Estadio Jose Amalfitani, Isgro said: "This weekend is going to be tougher and they're going to come with other things.
"We have to focus on ourselves. We made a lot of unforced errors in the match, and we have to work on that, on the details."
