"Britain will have to choose: stay in the single market and accept free movement or have another status."
Francois Hollande has told Theresa May that Britain's exit from the EU should happen "the sooner the better".
But at the Elysee Palace in Paris, the British Prime Minister reiterated the UK would not invoke Article 50 of the Lisbon Treaty, triggering Britain's EU withdrawal, this year.
At a joint news conference, the French president said Brexit was the decision of the British people and it needed to be respected.
He continued: "We would like it to be reflected in the best possible timescale to open a negotiation to establish what will be the relationship between the UK and European Union.
"The sooner the better in the common interest ... because uncertainty is the greatest danger."
Mr Hollande said there could be no access to the single market without allowing EU workers into Britain.
"It's the most crucial point," he said. "Britain will have to choose: stay in the single market and accept free movement or have another status."
Mrs May said that while she understood the need for "certainty and confidence" in the markets, it "will take time" for the UK to prepare for negotiations.
"Brexit means Brexit," she said, "and I firmly believe we will make the best of it. We will continue to work together."
She said she wanted to "maximise the opportunities for both the UK and the EU".
The Republican Guard was in position as Mr Hollande greeted the Prime Minister at his official residence.
In Dublin hours earlier for talks with Taoiseach Enda Kenny, Mr Hollande also called for negotiations on Britain's split from the EU to be as brief as possible.
In Berlin on Wednesday, during Mrs May's first foreign trip since taking office following Britain's seismic EU referendum last month, she encountered a more accommodating tone.
German Chancellor Angela Merkel told Mrs May she accepted that Britain needed to "take a moment" to prepare for the negotiations.