Opener Avishka Fernando top-scored with 76 while one-down Bhanuka Rajapaksa contributed a 56-ball 65 to help Sri Lanka score a consolation win.
Captain Dhawan, who very wisely dropped anchor and let the young guns express themselves, finished off the match in a professional manner with an unbeaten 86 off 95 balls.
Sanju could be ruled out of the white-ball series against Sri Lanka after he sustained a knee ligament injury during a training session.
A second-string India take on hosts Sri Lanka in a three-match ODI series starting Sunday.
The 26-year-old Kerala star gives a glimpse of his range of strokes in the video shared on his Facebook page.
The 26-year-old Sanju is in Mumbai undergoing a 14-day quarantine along with his teammates ahead of the Sri Lanka tour.
Sanju, who was dropped from the Indian T20I team after the tour of Australia, has earned a place in the squad based on his performances in IPL 2021.
Devdutt Padikkal, Chetan Sakaria, Nitish Rana, Krishnappa Gowtham and Ruturaj Gaikwad have received their maiden India call-ups.
BCCI chief Sourav Gaguly said that the Indian team, sans the top players, will tour Sri Lanka in July for a limited overs bilateral series.
The defending champions reached the target of 172 with nine balls to spare.