Speaking at the Bloomberg Global Business Forum at the Plaza Hotel in New York, Emmanuel Macron said Brexit "costs a lot" and is "much more complicated" than Leave campaigners initially thought.
The French leader said he would welcome another referendum but stressed it wasn't his decision to make.
"I am not the one to decide such a move and I do respect the choice of British voters. So I don't want to interfere in this debate about the second referendum and son on. I am respectful but I did regret this vote for the rest of Europe and for our special relationship — for France and UK."
When asked if he would welcome the UK back in the European Union, Macron said "for sure."
The French president was speaking at the Plaza Hotel, where the UK PM Theresa May delivered a speech to business leaders earlier in the day. She promised those investing in Britain the lowest corporate tax rate in the G20 and vouched that the "post-Brexit Britain will be unequivocally a pro-business Britain."
In her address, the British PM attempted to boost business confidence in future Britain, whose financial district and overall economy suffered from the inconsistencies and uncertainty surrounding the UK's post-Brexit future.
Commenting on whether France is luring "the bankers from the City of London to Paris," Macron said it "was about history, not domestic interests."
European leaders, including the French president, have last week rejected Theresa May's proposal on the future of UK-EU relationship, which fanned the flames of bitter political division in Westminster.
On Thursday, EU's chief negotiator Michel Barnier tweeted that the future EU-UK partnership should include a close economic link.
Good meeting w/ @MarotoReyes, Spanish Minister for Industry, Trade and Tourism. The EU continues to work for an orderly #Brexit and an ambitious future partnership with the UK that should include a close economic relationship. pic.twitter.com/bZsP4oDXNN— Michel Barnier (@MichelBarnier) September 27, 2018
However, the EU has also been reported to prepare for a possible collapse of Brexit talks, staring in November. Should no agreement with Britain emerge, the 27 states will step up contingency planning.
Britain is set to leave the EU on March 29, 2019, and by then is expected to reach a deal with the bloc that would secure "frictionless trade" as envisaged by Theresa May. If the two sides fail to reach a deal, UK will walk away from EU with nothing, something that is much feared in Westminster and the City of London.