Second-half goals from Winston Reid, Ricardo Vaz Te and a superb solo effort from Ravel Morrison sealed an impressive away win for the Hammers and condemned Spurs to their second league loss of the season.
The result leaves the north Londoners in sixth place in the table, three points behind early pace-setters Arsenal.
“It is [a wake-up call],” Villas-Boas said.
“This fixture was a bit dangerous. If we won everything it would be spectacular but if you draw or lose you drop into a position you don’t want to be. Either way we have done well so far.
“We have conceded three goals today but before we were the team who conceded the least chances. This time West Ham managed to surprise us and we have to bounce back. This would be a good goal for us.”
The Portuguese coach felt that his side conceded against the run of play at White Hart Lane.
“I think they scored in a moment when they were very, very strong – through set plays, they got first to the second ball,” he continued.
“It can happen in games like this. We didn’t have that quick reaction to get back into the game because they scored the second soon after.
“The game started 100 miles per hour for both teams, with both looking threatening. They had good spells and so did we. The second had we were not first to the ball in the 50-50 duels. They were a bit more aggressive and punished us.”
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