The Catalan club holds a nine-point lead over Diego Simeone's men at the top of the table thanks to Sunday's result, with defending champion Real Madrid trailing by 13.
"La Liga is only ours to lose," he is quoted as saying by AS.
"We're in a very favorable position, but we cannot lose a game. If we relax, the danger is that we go into a run where we don't win two or three games and lose our advantage.
"If we lose a game, nothing happens, but we cannot have a losing streak. We're having a great season. It's something else to watch my teammates."
Pique went on to say that Atletico, and Radamel Falcao in particular, were tough opponents, and admitted that the match might have been different had Adriano not cancelled out the Colombian's opener.
"The first half took it out of us," he continued. "Adriano's goal gave us a lot. We had a very good game against a great team who are second.
"[Falcao] is a great player - he's having a great season. He runs a lot, so you have to be wary. He's very difficult on the field."