The 27-year-old attacker has widely been regarded as one of Les Parisiens' standout players over the early stages of this season.
In six Ligue 1 matches this term, Dembele has already netted four goals and delivered four assists, including setting up Bradley Barcola for the side's opener against Rennes over the weekend.
However, widespread reports suggested that despite getting the win, the French international was left frustrated after being subbed off with just eight minutes left before the final whistle.
Enrique drops Dembele from Champions League squad
On Monday morning, L'Equipe reported that Enrique criticised some of Dembele's actions on the field against Rennes and was not pleased with the Frenchman's reaction to his feedback, leading to a heated confrontation between the two.
later in the day, the PSG boss confirmed that the 27-year-old France international, viewed as the club's most valuable player in the post-Kylian Mbappe era, did not make the trip to London.
Speaking from the Emirates Stadium ahead of Tuesday's clash with the Gunners, Enrique said: "If someone doesn't comply or respect the expectations of the team, it means they are not prepared to play.
"The match tomorrow is very important and I want all my players to be ready, so as a consequence I have left him (Dembele) out. I want the best for my team and that is my job."
When asked to explain the details of the altercation with Dembele, Enrique replied: "I am very honest and I will be honest, but I am not going to create a soap opera out of this.
"There are no problems between us. That is completely false. This is simply about the responsibilities of the player."
Dembele exclusion adds to PSG's lenghty absentee list
Unlike Arsenal, who drew their opening group stage match against Atalanta, PSG began their Champions League campaign with a victory, defeating Girona 1-0.
However, Les Parisiens will know they are in for a much more challenging encounter against the Premier League title contenders, especially with Dembele missing and Gianluigi Donnarumma, Marco Asensio and Desire Doue also considered doubtful for the match.
Additionally, PSG will also be without defenders Presnel Kimpembe and Lucas Hernandez, as well as striker Goncalo Ramos, all due to long-term injuries.
Mikel Arteta, meanwhile, is still without his captain Martin Odegaard and summer signing Mikel Merino in midfield, but he is optimistic about having Ben White and Riccardo Calafiori available for Tuesday's match.