Vinicius Jr's curled strike cancelled out Ismael Saibari's opener at East Rutherford, New Jersey, leaving both teams with one point from their first match of the tournament.
Scotland beat
"We did not play well: a few challenges, a very imbalanced team, we lost several balls and I think we have to do better in that sense," Ancelotti said.
Morocco took the lead in the 21st minute when Saibari finished a swift counter-attack, converting Brahim Diaz's through ball.
Vinicius equalised in the 32nd minute, cutting in from the left and curling a right-footed shot into the top corner.
Ancelotti said Brazil improved after halftime following several substitutions, but could not break down Morocco's low block.
"I am not disappointed by this result, and I'm not satisfied either," he said, adding that Brazil's starting lineup would not remain unchanged throughout the tournament.
"You don't win a World Cup based on your first match," he said, with Brazil next facing Haiti on Friday.