The 34-year-old, who recently won the Wimbledon, to add to his Australian Open and French Open crowns, added, "Cannot disappoint my little friend Koujirou.
"I think what hurt so much this time was just that I felt like the game is there and it's possible to go and play for the trophy," Shapovalov said on Friday evening.
After losing the first two sets 6-7(6), 2-6, the Serb left the Court Philippe-Chatrier for a break and returned a changed player as he downed fifth-seed Greek Stefanos Tsitsipas to win his second title
Djokovic has won the first two majors of the year, and at Wimbledon he'll have a chance to match the men's record of 20 Grand Slam titles shared by Nadal and Roger Federer
Nadal, who went into the match with 105-2 (win-loss) record and with a 7-1 record against the Serb, was the outright favourite to win the match and set up a final clash with Greek Stefanos Tsitsipas. For, he had lost only one set in this year's tournament
Djokovic overcame a cut in his left hand that saw his racquet dripping with blood immediately after the crowd had been cleared from the stands in the fourth set due to 11pm night curfew in Paris.