While May was returning from a holiday in Italy, it was Macron's first night at the Fort de Brégançon, an official presidential residence for the last 50 years.
The pair were to have a one-on-one meeting before dining with their spouses, Philip and Brigitte.
But no announcement on their talks was to be made, since the French government does not wish to "substitute itself for the process conducted by Michel Barnier", the official EU negotiator, a presidential statement said.
French Foreign Affairs Minister Nathalie Loiseau "confirmed France full support for Mr Barnier" and praised his "remarkable work" in a statement on Friday, the day after meeting British Brexit Minister Dominique Raab.
May spoke to EU Commission president Jean-Claude Juncker on the phone in Friday morning.
Irish border, financial services
Bank of England Governor Mark Carney warned Friday that the possibility of a no-deal Brexit is "uncomfortably high" and "highly undesirable", while adding that it is still "unlikely" compared to other outcomes.
Banks had been stress-tested for property prices falling by more than a third, interest rates going up by almost four percentage points, unemployment rising to 9.0 percent and the economy entering a 4.0 percent recession, he revealed.
The British government is concerned that a deal may not be reached and considers France as a hard-liner on several questions currently being negotiated.
Among them are Northern Ireland's border with the Republic of Ireland, which will remain in the EU, and financial services.
Paris, like Frankfurt, hopes to attract firms currently based in the City of London who wish to maintain a base inside the EU.
The two sides are supposed to reach agreement by the October European summit.
May is expected to raise her government White Paper published in July, which raised proposals for post-Brexit relations.
France, like the rest of the EU, is insisting that the terms of British withdrawal must be fixed first.