"The long-runs felt pretty OK, quite consistent", said Vettel.
"The game will be on TV here and l am sure my guys will try to keep an eye on both things at the same time - as will I".
"This place is handsome, it's really stunning down here", Hamilton said of a circuit that last hosted a grand prix in 1990 and represents a new challenge for a man who has won everywhere else on the calendar.
"Qualifying is always tough, but it feels great to be back in France", said Hamilton.
On an initially dry track following heavy rainstorms, which had curtailed final free practice, the air temperature was 22 degrees Celsius and the track 30 when qualifying began.More news: We are not afraid of Argentina - Super Eagles
"I was confident I could improve for the final attempt", Vettel said about his last flying lap that came up short.
Fernando Alonso, victor of the 24 Hour Le Mans last week, failed to get out of the first qualifying section, which culls the slowest five drivers, along with McLaren partner Stoffel Vandoorne and both Williams cars.
Vettel admitted he found it hard to get a good balance in France after managing third in Q3.
But Hamilton's mood later took a turn as he watched a replay of Vettel's crash with Bottas on the 210mph charge to the opening bend.
Good for Mercedes to hold their nerve despite the forecast for rain halfway through the race - they didn't call in their men to change their tyres or tactics.More news: Javier Hernández dreaming of 'the impossible' at World Cup
Hamilton, however, is seemingly certain to stay, and it is likely he will be partnered by Valtteri Bottas for a third year with Mercedes content that the inoffensive Finn is doing enough to retain his seat.
Grosjean's fellow FrenchmenEsteban Ocon and Pierre Gasly will start from 11th and 14th respectively.
There was also drama on track, with Swedish driver Marcus Ericsson crashing his Sauber in the first session and clambering out with the vehicle on fire.
Hamilton, armed with his new Mercedes engine, has been in emphatic form in France, and after topping both practice sessions on Friday, sticking his Mercedes on pole, and then nailing the start, his win never appeared in doubt. The pit stop dropped Bottas to last place and the resulting damage to the floor of his vehicle hindered his progression back through the field.More news: With luck, Harry Kane joins England's great World Cup strikers