The death toll in the London attack has risen to seven. Four French people were injured in the London attacks, one of them seriously, Foreign Affairs Minister Jean-Yves Le Drian said on Sunday morning.
"The attack which struck London ... is a new abominable, cowardly attack on our free societies," the French presidency said.
France "will continue to fight terrorism with all its powers, alongside the United Kingdom and all affected countries", Macron said.
Witnesses say three men in a white van rammed into pedestrians on London Bridge just after 10.00pm local time before proceeding to the nearby Borough Market where they stabbed several people before being shot dead by police.
The three men were wearing fake suicide vests, London's assistant police commissionner Marc Rowley said.
Two French nationals were injured and one of them is in a serious condition, presidential spokesman Christophe Castaner announced.
France is doing all it can to help those injured, the presidency says, adding that security would be tightened for expatriates voting in London on Sunday in the upcoming French parliamentary election.
Two weeks after Manchester attack
Saturday evening's attacks come just under two weeks after the Manchester attack which left 22 people dead and two months after a man killed five people by driving his car into them on Westminster Bridge in London.
It also comes five days before Britain is due to vote in a general election.
Britain's Prime Minister Theresa May offered her condoleances and returned to London for an emergency security meeting later today.
Her Conservative Party called off campaigning for the election.
London Mayor Sadiq Khan condemned the attacks as "barbaric" while the opposition Labour leader Jeremy Corbyn paid tribute to the emergency services and said his thoughts were with the victims and their families.
"Today we are united across borders in horror and mourning but also in determination," German Chancellor Angela Merkel said in a statement. "For Germany, I reiterate that in the fight against all forms of terrorism, we are resolutely at Britain's side."
US President Donald Trump tweeted that America would do whatever it could to help Britain.
But, as Washington correspondent Philip Crowther reports, Trump's call in the same tweet for his controversial travel ban on six mostly Muslim countries caused immediate controversy.