England's James Morrison was part of a four-way tie for the lead as the top 52 players were separated by just three shots after the opening round of the Trophee Hassan II.
Three more French players -- Alexander Levy, Clement Sordet and Gregory Bourdy -- were among a large group on two under, with Scotland's Scott Jamieson, David Drysdale and Duncan Stewart another stroke back.
Havret said: "It's good to play under par, anything in the red here is very good on a very tough course, so I'm happy.
"This course always plays hard and since the changes a few years ago it's even harder. When the wind is changing it's not easy to find the right club.
"It's in perfect condition, the course is just in great shape and we always enjoy it here. It's definitely a test of golf. I think it's one of the toughest all season."
Levy has not played since finishing fourth in Malaysia in the middle of February, but showed few ill effects as he carded four birdies and an eagle in his 71.
"I've had eight weeks off, I've practised a lot and changed coach so it's nice to come back out to play a tournament," Levy said. "It's exciting to bring all that hard work over the last eight weeks back out on the golf course."
Defending champion Jeunghun Wang, who missed the cut on his Masters debut last week, faces a battle to avoid another early exit after struggling to a four-over-par 77.
And former Masters champion Mike Weir, who has not made a cut since November 2014, fared even worse with six bogeys and a double bogey in an 81.
The Canadian left-hander, who defeated Len Mattiace in a playoff at Augusta National in 2003, has been as high as fourth in the world, but is currently ranked 1,895th.