Swansea City had Jonathan de Guzman clean through on goal just as referee Lee Probert called an end to the 2-2 draw with the Gunners, though the manager is pleased with a point.
Lukas Podolski and Olivier Giroud found the net in the space of one second-half minute to turn the game on its head after Wilfried Bony had given the Swans an early lead but Mathieu Flamini scored an own goal to pull the visitors level at the death.
However, referee Lee Probert then blew for full-time with Swansea's Jonathan de Guzman clean through on goal just inside the Arsenal half, with Monk fuming to reporters that it was a "very poor decision".
"First half, they added two minutes on because of our goal - fair enough," he continued, "so they told us it was going to be four minutes at the end of the game - OK. We score in that period so they add an extra minute on so that's five minutes minimum - I'll stress the word 'minimum' - and then we're clean through on goal, 99 per ent a goalscoring opportunity is going to come and they blow up 30 seconds short.
"A very poor decision, as simple as that. I'm not going to say whether he's going to score the goal or not - I can't predict that - but it's definitely going to be a shot on goal."
Probert was surrounded by Swansea players at the final whistle but Monk concedes that he was ultimately happy to have registered an important point, which lifts them five clear of the relegation zone.
"If you offered us a point before the game we would have said yes," he accepted. "Every point is vital. "I had more belief in this team than a lot of other people and I know what they can do and they showed that.
"My final word before they went out was to be together and do it for each other because, at the end of the day, when you're out there, that's all you've got and they did it to a man."