Oleksandr Zinchenko (pictured with Arsenal boss Mikel Arteta) had argued with team-mate Ben White about the goal scored by Nottingham Forest
The Gunners closed the gap on Premier League leaders Liverpool to two points after an impressive second-half show cracked Forest's resistance at the City Ground.
But, after leading 2-0 through Gabriel Jesus and Bukayo Saka, the visitors conceded late on when substitute Taiwo Awoniyi struck.
After the full-time whistle, Arsenal's celebrations were cut short when White and Zinchenko had to be separated after arguing about the hosts' late goal.
Arteta said: "I love it, they demand more from each other and they are not happy with the way they concede that and they are trying to resolve it.
"It was a bit heated, but that means it is not enough playing the way we played, the result has to be bigger.
"That's pushing each other and not being happy conceding and I have to encourage that and promote it in the right way and a respectful way.
"Sometimes after the game it's emotional and heated, but I love that the players are pushing each other and demanding excellence."
The Gunners initially struggled to break down Forest's well-organised rearguard but took the lead after 65 minutes when home keeper Matt Turner allowed Jesus' low shot to deflect in as it slipped through his legs at the near post.
Arsenal doubled their lead seven minutes later, cashing in ruthlessly on another Forest error after Gonzalo Montiel gifted possession to Martin Odegaard, his pass setting up Jesus to play in Saka for a confident finish across Turner.
Forest substitute Awoniyi grabbed a goal back with a close-range finish in the dying moments and almost levelled from a similar position just moments after, but Gunners keeper David Raya was equal to it.
Arteta's celebrations at full-time illustrated just how much the win meant in a meeting with a Forest team whose victory here last season ended Arsenal's title challenge.
Liverpool could re-establish their five-point advantage at the top with victory over Chelsea at Anfield on Wednesday, but this win provides the perfect platform for when Jurgen Klopp's side visit Emirates Stadium at the weekend.
-- Courtesy of BBC Sport