Gabriel has told his Arsenal teammates to put their disappointing Olympiacos result to one side and focus on making amends in Sunday's visit of Manchester United.
The Gunners' hopes of reaching the last 16 of the Champions League suffered a blow on Tuesday after their 3-2 defeat to the Greek side at the Emirates.
With the Red Devils on the horizon, Gabriel feels that there is little time for his teammates to lick their wounds and demands a swift response against the Premier League leaders.
"It was a complicated night [against Olympiacos]," he told Arsenal's official website. "We were in a good place in the first half, defending well, we were happy. But the three goals were our own fault.
"We only have ourselves to blame for conceding them and now we have to rest, work harder, and then on Sunday come back and have a good game.
"We just need to be calm. We have to work hard and focus on putting in a good performance [against Manchester United]."
Arsene Wenger's side sit bottom of Group F with zero points from a possible six, having already lost to third-placed Dinamo Zagreb.
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