Goals from Clayton Donaldson, Marcello Trotta and Sam Saunders gave Mark Warburton's side a three-goal cushion before Lee Hodson's reply for the visitors.
Robinson admitted his team had been 'blown out of the water' by the Bees but he hailed his side's character for a late fightback that almost gave them a foothold in the game.
"We didn't start well and their first goal was a comedy of errors," said Robinson. "Having said that I don't want to take anything away from Brentford, who were sensational for the first hour.
"We were blown out of the water and they were by far the better team for more than an hour, but when we started to play we caused them a lot of problems."
Hodson replied for the Dons in the 73rd minute with a rasping drive that beat Brentford goalkeeper David Button at his near post as the visitors looked for an unlikely way back into the game.
Dons dangerman Patrick Bamford screwed a shot wide when clean through before seeing a strong penalty shout waved away by referee Andy D'Urso as the game drifted away from Robinson's side.
The Dons boss added: "For most of the game they were outstanding, but we made mistakes and we will work on those to make sure we get better.
"We are good when we play at a high tempo and move the ball quickly, and in the main we did that. We will look at where we didn't and put it right."