The Bees took the lead in the first half through Alan Connell as the Dons struggled to make any impact in the game.
They improved after the break and got an equaliser through Kevin Gallen, but couldn't find a winner against a Brentford side who came to frustrate them.
The Dons did try to get into their passing game from the off and created some decent chances.
After five minutes, Keith Andrews just scuffed a 25-yard shot wide after Dean Lewington squared to him from a free-kick.
On nine minutes, Gallen turned well in the box but his shot sailed well over the bar.
Then against the run of play, ex-Don Gary Smith put Tony Thorpe clean through on goal, but Willy Gueret came out well and blocked his shot.
The Bees then went one better straight after and took the lead on 16 minutes.
Thorpe was again involved as he headed a long ball down to Connell, who superbly half-volleyed into the top corner.
The Dons had a great chance to equalise on the half-hour mark when Lloyd Dyer went through on goal and rounded Simon Brown but Ben Starosta cleared well off the line.
Minutes later, Smith put Glenn Poole through one-on-one with Gueret but the keeper made himself big again and saved well.
Then on the stroke of half-time, Mark Wright feebly headed wide from 10 yards after Jude Stirling's cross.
The Dons really upped their game after the break, immediately penning the Bees in their own box and Gallen should have done better with a free header from Wright's cross but he completely missed the ball.
The Dons continued to huff and puff, but with the visitors defending so deep they struggled to create anything.
But then on 68 minutes their patience paid off when Wright's low cross found Andrews who spun well and laid off for Gallen to side-foot well into the far corner.
There only looked like being one winner now and the Dons continued to pile forward with Andrews having a decent chance that he volleyed wide from the edge of the box.
But to Brentford's credit they continued to defend resolutely and the only near-miss came when Ryan Dickson almost sliced into his own net from Wright's cross.