Pakistan also reached the semi-finals, crushing Hong Kong by 68 runs with experienced all-rounder Khushdil Shah taking 3-13.
With superstars such as Rohit Sharma and Virat Kohli at home for the one-day World Cup beginning on Thursday, India, the world's top-ranked Twenty20 team, have a second-string squad in Hangzhou.
But it is still formidable, packed with promising youngsters who have excelled in the Indian Premier League and a host of players with international experience.
After winning the toss and opting to bat, Jaiswal's masterful 100, from 49 balls, plus late fireworks from Rinku Singh (37 not out) and Shivam Dube (25 not out) helped them to 202-4.
Nepal had bludgeoned a record 314-3 against Mongolia in the qualifying rounds, but they could only manage 179-9 in reply, with Avesh Khan and Ravi Bishnoi taking three wickets each.
"They are a good side so we're not surprised at how they came at us," said India skipper Ruturaj Gaikwad. "It wasn't our best day but we still managed to get a win."
Cricket has been played at the Asian Games twice before, at Guangzhou 2010 and Incheon 2014, but India did not take part.
Bangladesh won the men's title in 2010 while Sri Lanka are defending champions, with Afghanistan runners-up both times.
Along with Pakistan, Sri Lanka and Bangladesh, India entered the Hangzhou Games at the quarter-final stage.
Pakistan swept through at an overcast Zhejiang University of Technology Pingfeng Cricket Field, despite some early wobbles.
They struggled on an uneven pitch and slumped to 54-5 after being sent in, but a brilliant 41 from 16 balls by Aamer Jamal ensured they made a respectable 160 all out.
Hong Kong similarly collapsed, to 55-5, but they had no-one of Jamal's class to bail them out and were bowled for 92.
"It was a combined job by all of us," said Pakistan opener Omair Yousuf.
Jaiswal got India off to a scorching start and they were cruising at 103 without loss.
But when Gaikwad fell slogging to deep mid-wicket on 25 it sparked a mini-collapse with Tilak Varma (two) and Jitesh Sharma (five) soon following.
At the other end, Jaiswal, who played in the Test and T20 series against the West Indies in July, smacked seven sixes and eight fours in his ton.
The 21-year-old's luck ran out soon after, caught on the ropes by Abinash Bohara.
That brought Kolkata Knight Riders star Rinku to the crease and he slammed 37 off 15 balls in a late flurry.
"Wherever you go and score a century, especially when you are representing your country, it's a proud moment and you get goose bumps," said Jaiswal.
In reply, Nepal were motoring at 62-1 in the eighth over, but the introduction of leg-spinner Bishnoi put the brakes on.
He snared captain Rohit Paudel and crucially Kushal Malla -- who slammed the fastest-ever T20 international century, off 34 balls, in a record-breaking win at the Games over Mongolia -- for 29.
It left Nepal in trouble at 77-4 and while Dipendra Airee (32) and Sundeep Jora (29) did their best, it was not enough.
Sri Lanka face Afghanistan and Bangladesh take on Malaysia in the other quarter-finals on Wednesday.
© 2023 AFP
