Fiji had nearly no possession in the first half - making only four passes to Kenya's 20 - but managed two breakaway tries from kickoffs to keep the match in the balance at halftime.
The All Blacks Sevens had plenty of possession in both games but were unable to crack the defence of both the US and England. "All the teams now are very hard to play against, not like before".
After the final, Tuwai said he was proud of his young side.
A quick penalty take from Eden Agero set up Oscar Ouma for the first try for head coach Innocent Simiyu's charges with the skipper running under the posts as Oliech added the extras.
The World Series Standing after the Canada Sevens. Samuel Oliech added the conversion for Kenya's 7-0 lead.Fiji responded nearly instantly through Josua Vakurunabili's try and Vatemo Ravouvou conversion to even the proceedings.
Mocenacagi clinched the Man of the Match award when he scored again two minutes into the second half, supporting Amenoni Nasisila, who handled twice in the build-up. Paula Dranisinukula then showed his strength by defying three tacklers to score Fiji's last try.
The win puts Fiji at second place to South Africa in the World Series Standing.
South Africa responded with two tries from Siviwe Soyizwapi and tries from Cecil Afrika and Dylan Sage - Sage scoring well after the siren to extinguish Australian hopes.
The Blitzboks, who beat the United States 29-7 in the bronze medal game, maintained their lead on 109 points, with Fiji just eight back at 101 and New Zealand third on 92.
The next tournament beings in Hong Kong on April 6.