The likes of Reiss Nelson, Bukayo Saka, Joe Willock and Emile Smith-Rowe are among the next generation at the Emirates Stadium club.
But Ljungberg believes that given they have such little senior football experience, big games are a challenge for them to handle.
Many of the youngsters were involved in the Gunners' 2-2 draw with Standard Liege in the Champions League on Thursday night.
"I feel sorry for our young players," he told reporters.
"A lot of them haven't been on loan, they've not had that exposure to men's football.
"Some of them made mistakes but they'll learn from those mistakes and won't do them again."