Spurs were pegged back twice on Saturday, with the point leaving them inside the bottom three, one point from safety.
De Zerbi said: “We played very well. I think we deserved to win this game. I'm disappointed just for the players and the fans because, for me, nothing changes. I'm positive. I believe in my players, not just now after this game, but before coming here.
“We have time enough to reach the target. We have the qualities enough to reach the target. We have to be strong and to be positive and not to be sad and not to be negative and to help inside on the pitch, the changing room, to keep this atmosphere and to come on Monday afternoon with a smile. Otherwise, they don't work with me.
“I said like this inside the dressing room because after one game like this, after the mentality and the spirit they showed, now we have to believe in the target.”
On the way Tottenham created both of their goals, De Zerbi added: “I'm pleased for the pressure. I think we can press higher again. We can play better with the bal. We can improve with the ball.
"We are not working so much in the build-up, because I don't want to give too much information, to give too much instruction. They have to play with confidence and freedom.”