Plymouth manager John Sheridan described his side as "lethargic" and "poor" in the 2-0 loss at Dagenham.
The defeat, their third in the last five games, saw the Pilgrims drop out of the play-off places.
"For where we are and what's at stake, I just think it was a very lethargic performance," Sheridan told BBC Devon.
"A lot of fans have come here but it was a poor performance. They know the importance of the game and I accept their disappointment," he added.
Having won four games in succession during February, the Pilgrims have picked up maximum points just once since. They are now a point behind Stevenage, who occupy the final play-off place.
"I didn't expect us to get no points from the last two games," Sheridan said. "But while there's still a chance and a possibility (of the play-offs) I've got to stay focused and keep the players focused and it's onto the next game with Newport.
"But that wasn't a performance from a team that's trying to push to get into the play-offs."
But Sheridan did single out teenage loanee Tareiq Holmes-Dennis for praise after the game, adding: "He had a bit of desire about him. I hope some of the other players look at him and learn from a 19-year-old.
"I've told him in there 'don't change your attitude because you'll go far in the game with that attitude'."