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."
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."
