It was Boro's first away win of the season - taking them to third in the Premiership -and Tottenham's first defeat at home.
McClaren said: ""I feel sorry for Spurs because they caught us on a very good day.
"I give full credit to the players and the only disappointment I have is that we didn't score more goals.
"In that way it was a bit like our game at Everton a few weeks ago when we missed lots of chances after dominating but the lads have learned from that."
Italian striker Massimo Maccarone, Boro's £8.1million signing, led the charge with the opening goal - his fourth of the season - and McClaren said: "We're delighted with him. He's done very well. You certainly can't argue with the way he took his goal and I believe he had a hand in the other two as well."
McClaren was more cautious than Boro's jubilant travelling fans. He said: "We've set a benchmark and we're third in the table, but it is only after eight games. I'd be sat here ecstatic if it was the end of the season and we were still third.
"There is still a long way to go but we've shown the quality of our football a few times already this season and it's been a very satisfactory start."
Middlesbrough boss Steve McClaren saluted his side after a resounding 3-0 win at White Hart Lane and said: "I feel sorry for Spurs because they caught us on a very good day".