Sunday's race will be hard to win from the second row but Vettel said he would do all he could to eat into Hamilton's championship lead.
Hartely lamented a lack of pace and conceded a tyre strategy didn't work out.
"Going into detail, I don't think there's much point ... maybe with preparing the qualifying", he said.
The Ferrari pairing of Vettel and Kimi Raikkonen had set the pace for most of the weekend but the German could manage only third place, more than half a second down, and will start alongside Mercedes's Valtteri Bottas. "I don't know where it came from but it all came together".
The Briton maintained breathing space between him and Vettel after the restart, extending it to more than two seconds by lap 13 at the Marina Bay Street Circuit.
Hurricane Florence rolls ashore in Carolinas, tears buildings apart
In Jacksonville, a relentless band of heavy rain gutted buildings, drenched streets and left wildlife to battle the rising waters. Farther up the coast, in New Bern, about 150 people waited to be rescued from flooding on the Neuse River, WXII-TV reported .
Verstappen was twitchy from the off after Vettel's swing past, informing his team, "The auto feels really good!"
"I said before the weekend we can only beat ourselves and we didn't get everything out of our package".
"I don't want to take anything away from Lewis and their efforts as a team". "I know that not a single member of the hierarchy, like [strategist] James Vowles or Toto probably, really didn't think that was possible - maybe more of them. All we can hope for if the cars in front, their tyres fall away and they're forced then to do a two-stop, otherwise, if everyone does a one-stop, hope for someone to run on the track like they did in 2015 I guess". The safety auto has been a regular feature here in the last 10 years and it was no different this time when Sergio Perez pushed his Force India teammate Esteban Ocon into the wall after Turn 3 on the opening lap, reminding of their heated battles last year, after which the Silverstone squad was forced to implement team orders.
Vettel arrived in steamy Singapore 30 points behind the Englishman but with high expectations of clawing back ground on a circuit expected to favour his Ferrari. "Definitely that put us second today".
Vettel conceded Ferrari had made tactical errors in qualifying but argued that although Hamilton's pole lap was significantly faster than his, the Briton was not untouchable.
Josh Gordon Release: Why Did the Browns Cut the WR?
The news came several hours after Gordon was listed as out for Sunday's Week 2 game at New Orleans due to a hamstring injury. For as much talent as Gordon has, this also has as much to do about the future of the Browns as it does Gordon.
The 20-year-old apologized to his team on the radio as he left his auto stranded in an escape road with two minutes left in the session, a sight that will disappoint his future employers, who will hope he does not make similar mistakes next season.
"My heart's racing, I'm having an anxiety attack", Hamilton said, letting out a laugh of relief. The second lap I tried to obviously go that little bit more.
Vettel's frustration increased as Hamilton rejoined in front and then boiled over as Verstappen jumped him when he too pitted for softs.
Verstappen was the next in, nearly colliding again with Vettel into turn three. "Because they did great and that's why they are on pole by quite a margin".
First Hurricane Florence deaths: mother, infant killed by tree
Henry McMaster has not yet lifted the evacuation order he put in place Tuesday, and it is not clear when the order will be lifted. In Hampstead, North Carolina, emergency responders going to a call for cardiac arrest found their path blocked by downed trees.