Ibrahimovic was on target two times in three minutes midway through an entertaining first half after Gignac's solo effort had put the home side ahead in the 17th.
The Swede equalised on 23 minutes with a stunning backheel volley from a corner then put PSG in front two minutes later when he fired a free kick home from 25 metres.
Gignac answered in the 37th when he headed home a Benoit Cheyrou corner to keep Marseille at the top of the table on 19 points, three ahead of unbeaten PSG.
Marseille had dominated the first half but were visibly satisfied with the result.
"We were brave, we gave everything. We deserved to draw," Marseille's midfielder Benoit Cheyou told French channel Canal+.
"Pundits predicted us a 4-0, 5-0 or 6-0 loss. It was important not to lose, were we not able to win this match."
PSG substitute Kevin Gameiro had the only clear-cut chance of a dull second half but his strike went wide.
"The draw is logical. We were a bit tired in the second half and we lacked the briskness to break into Marseille's defence," coach Carlo Ancelotti said.
"Our last two games showed that we still have to improve," he added, referring to PSG's Champions League 1-0 at Porto on Wednesday.