French far-right presidential candidate Marine Le Pen says all the presidential contenders - and all French people - are potential attack targets.
The four-candidate battle to reach the run-off in France's presidential election is putting pollsters to the test as never before.
The new hardline tack has gained approval from her fans, with many at the Marseille rally chanting "la France aux francais" (France for the French), an old slogan associated with the xenophobia and anti-Semitism that infected the Front National when it was led by Mr Le Pen.
Macron said Obama wanted to exchange views about the French presidential campaign and that the ex-president had stressed how important the relationship between the two countries was.
If no candidate wins more than 50 percent of the vote on Sunday, there will be a run-off election between the two top vote-getters on May 7.
She has linked the terrorism arrests yesterday to immigration.
In a statement, Macron insisted on the importance of respecting France's secular traditions but said they shouldn't be used to target Muslims. A defeat by Hamon could crush the party of unpopular Socialist President Francois Hollande, who chose not to seek a second term.
The Grand Mosque of Lyon issued an appeal urging Muslims to cast ballots instead of isolating themselves, "so that all the children of France, regardless of their skin color, their origins or their religion, are fully involved in the future of their country".
Leader of the National Front, Ms Le Pen, said she wanted to be president of France, "not the European Commission", according to reports. "A peaceful and democratic uprising to give France back to its people", she said, "a day of glory will arrive".