Defender Per Mertesacker believes the Gunners should have been less adventurous in their second half approach against Monaco.
Geoffrey Kondogbia's deflected shot gave Monaco the lead in the 38th minute.
And it didn't take long for the visitors to double their lead after Arsenal opted for an all-out-attack approach early in the second half.
And the 30-year-old admits the defeat is hard to take ahead of the second leg at the Stade Louis II.
"Overall it's very disappointing for us," Mertesacker told the club's official website.
"We came out quite well, tried to put pressure on them and created a few half-chances. After, we dropped and fought not to concede.
"That would have been the key for us, then we conceded that goal with a heavy deflection - but that can happen. I thought in the second half we exaggerated a bit, looked a bit over motivated at times and they got us on the break.
"That's what we expected, but when you try to come back as quickly as possible, you can make some mistakes. That's what hurt at the end.
"We never give up. That's always the sense of our game, even if the expectations will be low now.
"It's easy to write us off now but it's just half-time. A lot of things can happen over there and we will try.
"As we have seen we have been remarkable at bouncing back from disappointing results. That will be the key - to be absolutely brave and try to be on the front foot from the start to the end.
"There are still 90 minutes to play. That is our big target there."
If they are to avoid another Last 16 exit, Arsenal must score at least three goals when they face Monaco in the second leg on March 17.
