Spurs were beaten by a 13th-minute Loic Remy goal and denied an equaliser by a fine performance from visiting goalkeeper Tim Krul, who made 14 saves.
The Portuguese refused to be critical of his side and lamented Tottenham's poor fortune, particularly in a second half where they applied plenty of pressure.
"We gave the first-half advantage to Newcastle but I thought we were very, very unlucky," said Villas-Boas.
"We had so many good chances; the result was very unfair."
The defeat meant Spurs missed the chance to return to the top four, as their impressive home form against Newcastle came to an end.
Spurs had beaten Newcastle in their previous four league fixtures at White Hart Lane, and Villas-Boas praised the visitors' performance on this occasion.
"Newcastle came in strong and played well first half - they deserved the lead," he continued.
"We did not recognise ourselves; we were not on top of our game, and it was not our better first half.
"Tim Krul did well today. Last season he had a great game against us as well.
"He was the inspiration; he made the difference. With a bit more luck we would have found the finishing touch."
