Tim Bontemps of ESPN.com provided postgame comments from Nowitzki, who missed all 10 of his shots en route to a scoreless outing in the Mavs' 114-93 road loss.
"Yeah, I mean super sweet, super emotional," he said. "It's sweet when not only your home fans, but the fans on the road, that appreciate what you've done in the last two decades. I appreciate the fans of Boston and, unfortunately, really disappointed I couldn't even make one."
Nowitzki could have passed longtime Los Angeles Lakers superstar and fellow future Hall of Famer Kobe Bryant for the most points at TD Garden by a Western Conference player with two points Friday.
"Just real disappointing, but definitely will never forget the reception and, obviously, at the end how they wanted me to break the record. I really appreciate it," he said, per Bontemps.
Celtics head coach Brad Stevens added he was rooting for Nowitzki to score a bucket late in the fourth quarter with the result no longer in doubt.
"I've rooted for the opponent to score two times in my life: Paul Pierce and Dirk Nowitzki," Stevens said. "I was sitting over there like everyone else in the building saying, 'Go in. Go in.' Right? But what a special player. Kudos to him."
Nowitzki is no longer the player he was during his peak, averaging a career-low 4.1 points across 10 appearances since recovering from offseason ankle surgery.
Although the 40-year-old Germany native hasn't officially announced he'll retire at season's end, Bontemps noted "all signs" point to the end of his career, and fans have treated it like a farewell tour.
Nowitzki couldn't pass Bryant, but it was still a memorable sendoff from the Boston faithful.