Before the Omnicom deal, Naouri had been seen as a potential successor to Levy, but he had failed to secure a prominent role under the merger plan. The deal fell apart this year over leadership conflicts that deepened during delays to tax and antitrust approvals.
Publicis also said it was hiring Axel Duroux "to take over strategy, development, performance and optimization of the Groupe's presence in emerging and fast-growing markets". This role had been filled by Naouri.
Read MoreOmnicom, Publicis call off proposed $35 billion merger
The company said it would present its plans to investors before the end of October.
"It looks like Levy's staying on a bit longer than people had expected for continuity and to get the company back on its feet," said Kepler Cheuvreux analyst Conor O'Shea.
"It's broadly reassuring. It looks as if what they're doing is going back to the business plan they set out in April 2013, before Omnicom," said O'Shea.
"The thing everyone wants to know is will they buy Criteo. They're not ruling it out, but maybe by publicly affirming these self-help targets they are suggesting they're not going to do that," he said.
Online advertising group Criteo SA's shares leapt in August after French media reported Publicis was in talks to buy it.
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