Trossard scored for the Gunners, though Palace twice came from behind to earn the point.
Afterwards, the Belgium attacker says they focus should now be on their Champions League semifinal with PSG next week.
“I think overall it wasn't a great performance by us today,” Trossard said at the final whistle. “It should have been better, especially if you have the lead twice, you need to defend it well. It's not what we did, but we just need to focus now on the next game.
“We just need to start better after that (first) goal as well, to focus on the simple things. I think we might, as a team, take it too easy. Then you see they have the quality as well to punish us, and that's what happened.
“Obviously it needs to be better. Especially with the big game coming up, we need to rest up and prepare for that one.”
He added, “It's always nice to be on the scoresheet, as I said in the other game as well, and to help your team moving forward. I'm pleased with that, but just not with the results.”
Now for PSG
Trossard says now the Gunners' total focus is on PSG next week.
“I think everyone is up for it,” he said. “We've now got a six-day lead up to it, we need to rest up now, prepare really well, and I think everyone will be up for it.
"With the home crowd behind us, there needs to be an electric atmosphere, and they will push us forward.
“We want the same as last time, they were incredible in the home game against Madrid. If we can do that again, it would be amazing.”