United meet West Ham on Sunday having won once in the last seven games.
"Yes, it holds us back in our levels and also in our position in the league," said Ten Hag of their injury-list. "When you don’t have the players available, you can't line up the best team.
"We need more players available often.
"We all have to work together on this point - the players, the coaching staff and all the other staff.
"We have to do better at that because we know when we have them we are a really tough team to play and we can be really successful."
Ten Hag also insists their record deserves better credit, despite the home defeat to Tottenham.
"I deny that game," he said. "I ignore that game against Spurs because we were downsized to 10 and the red card was overturned.
"It is not a fair assessment of the team to take this into consideration because we didn’t have the chance to bounce back. Of course, it was a tough first half, but in that period is also remember some very good chances.
"But you see this team is resilient and determined. Against Brentford and in tough away games, this team has showed character, fighting spirit and determination to win games."