"But so far from the look of it... There are things that point in the very right direction," she said.
Hard-charging Vestager, a former Danish finance minister, hit Google with the mega fine in June for illegally favouring its shopping service in search results.
Google, which was given 90 days to comply or face further fines, submitted details of its offer to the EU last week, which Vestager said her teams were carefully evaluating.
"We are in the process to see if they are sort of on the right track, but we do not approve it before they go ahead," Vestager told AFP during an interview at her office at EU headquarters.
"It is for Google to take their responsibility to comply," she said.
The fine over Google Shopping broke the previous European Union record for a monopoly case against US chipmaker Intel of 1.06 billion euros in 2009 and made the EU the global leader in regulating Silicon Valley giants.
Brussels accuses Google of giving its own service too much priority in search results to the detriment of other price comparison services, such as TripAdvisor and Expedia.
The verdict came less than a year after Vestager shocked Washington and the world with an order that iPhone manufacturer Apple repay 13 billion euros in back taxes in Ireland -- against Dublin's wishes.
Vestager insisted that the issue "will not delay anything" in a separate case over Google's Android mobile operating system.
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