Mikel Arteta said he was in “shock” and branded Arsenal’s performance in their 3-0 home defeat by Liverpool as “unacceptable”.
The Gunners, nine points off a Champions League spot with eight games left, were outclassed as they conceded three times in the second half.
“They were much better than us in every single department. I’m fully responsible for that,” said Arteta.
“We want to apologise, to our people and our fans.”
The Gunners are ninth in the table and their only realistic hope of securing a Champions League place is by winning the Europa League.
They host Slavia Prague in the quarter-final first leg on Thursday (20:00 BST).
Arteta is demanding an immediate response from his players after a dreadful performance against Liverpool.
“Today was a big shock in the system,” he added. “At the moment I’m in shock because I didn’t expect that.
“For sure we cannot hit that level again. To represent this football club and people who love this club, that was not acceptable. You have to stand up and take the challenge.
“It’s my job to make things better. Today we hit a really low level.”
‘Players didn’t believe in Arteta’s tactics’
Jermaine Jenas, former England and Tottenham midfielder on Match of the Day
I watched a team that didn’t believe in the tactics that were set out by Mikel Arteta.
I thought the body language from Arsenal’s players was poor. They didn’t seem to have any urgency to want to play or get on the ball or help the person on the ball.
I imagine Arsenal fans are sick of this now. How often have we seen Arsenal give the ball away from the back and concede goals? It’s getting to the point where it is getting ridiculous.