Ibrahimovic was on target twice 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 told a news conference.
"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.
Former Arsenal striker Jeremy Aliadiere's goal ensured Lorient continued their unbeaten run with a 1-1 draw at home to Olympique Lyon, who stay third on 15 points.
Lyon took the lead through France's Bafetimbi Gomis volley in the 23rd minute after a superb collective move.
Lorient levelled the score two minutes after the break when Aliadiere tapped in Benjamin Corgnet's neat pass to take his side up to fourth in the table on 14 points.
Both sides had a flurry of clear-cut chances in an action-packed clash at rainy Lorient.
Lyon, who suffered their first league loss last weekend, were unlucky to see Gomis's half-volley and then a fine lob from Clement Grenier hit the woodwork early on.
However, their efforts were rewarded when Alexandre Lacazette volleyed a Steed Malbranque cross to set up Gomis for the opener.
Inspired by Aliadiere and Alain Traore, Lorient reacted but the latter's powerful shot from outside the box struck the woodwork.
The hosts equalised just after the break and tightened their grip on play although they lacked a finishing touch.
Along with PSG and Lorient, Girondins Bordeaux are the other team unbeaten after they recovered from a goal down to draw 1-1 at Stade Brest, their fifth in the last six league games, which put them sixth on 14 points.
Well-organised Brest went ahead when Eden Ben Basat ran on behind the defence to shoot past keeper Cedric Carrasso in the 37th minute.
Bordeaux wasted several chances and saw an early Cheick Diabate effort hit the post but the player netted a
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