Although the Argentine boss admitted that their level dropped in the second period of the contest, he was happy with the way they started the match.
“Our first half was fantastic and our second half we need to analyse – I want to see the game again," he said.
“[Am I] concerned? No. In football you can always improve. After the first half we were happy in the stadium but in the second half it was not the same, it was a bad night for us.”
Tottenham had taken the lead against Newcastle when Eric Dier powered home a header from a corner.
It seemed then that they would go on to extend their unbeaten run in the Premier League to 15 matches, but they took their foot off the gas and were ultimately made to pay.
Newcastle scored two late goals through Aleksandar Mitrovic and Ayoze Perez to steal the three points and condemn Spurs to their first defeat since August.
The loss leaves Tottenham in fifth place in the Premier League table – three points away from the Champions League qualification spots but with plenty of football still to be played.