Emery said: "We didn't control the game in the first half. We were not progressing to impose our position. When they are connecting with their attacking players, they scored one goal.
"We changed tactics in the second half and we got chances to score a goal and in the end we did score. The second half, we deserve it more than the first half. The referee decided it was handball.
"We had a plan before the match and the plan can change. The players had to be ready and focussed in case we needed them like today. Zaniolo is working and he is focused.
"In this Premier League level it is difficult because the set piece takers are good. It is important to not concede set pieces. Overall, I think tactically in the second half we dominated and imposed our position.
"It's better to win but we draw and I think it's good and we have to accept it."