Rosler admitted that Preston deserved to go in front but his side's improvement meant that the draw was a fair result.
"I think in the first half, we were under par," London24.com quotes Rosler as saying. "They put pressure on us without creating big chances.
"Their chances came from mistakes. They were the better team in the first half but we got on top in the second half.
"We had more of the running [after the break]. Some of the players tired out a little bit, but Jeffrey Monakana was very good going forward.
Brentford are currently ninth in League One.