Despite being held, Fulham all but extended their season with Leeds needing a 13-goal swing on the final day of the season.
But the Fulham manager said: "In football many strange things can happen, but I don't expect that to happen next week. We will start thinking of the play-offs but we must not stand still.
"Are we the team to fear? Yes. We are in good form and we play with confidence.
"There is no need for us to do too many different things.
"I have never played the play-offs, it is my first experience of this competitions.
"It is 25 per cent for all the teams, you will play against more quality teams and you are going to start the most important part of the competition when we start the play-offs.
"I cannot be satisfied with the result but for another side, this is what I ordered my players to do. We didn't finish some actions, we made one mistake and they punished us hard.
"We are not at Wembley right now, we need to be ready to play at Sheffield Wednesday in our final game."
Fulham led via Cairney's eighth-minute strike but missed of host of chances with Floyd Ayite the main culprit before and after Yennaris had drawn Brentford level after 34 minutes.
But Cairney missed a penalty right on half-time, Fulham's ninth failure this season, after a fine save from Dan Bentley.
And the Brentford goalkeeper continued that theme in the second half to frustrate Stefan Johansen and Cairney.
Brentford manager Dean Smith said: "It was a different performance than we have put on in recent weeks. It was fast-flowing and attacking football, but we also had to defend resolutely at times.
"As a defensive unit we gave a few chances in the first half. In the second half they troubled us from distance. So really pleased to come here unbeaten and get a point.
"We were down to the bare bones in the end. We lost Rico Henry while Ryan Woods also pulled up. So credit to the players who took their opportunity and put in a good shift.
"If you have been watching Fulham as an attacking force, they have players full of pace and trickery. It was always going to be tough.
"We are finishing the season well. We didn't want to come here and allow Fulham to have party at our expense. They have made it but with other results. The players gave me everything."