The maverick has accused the presidency of being behind anti-corruption raids on his home and party head office earlier this month, which he said was a politically-motivated act.
He told supporters at a rally in the northern French town of Lille: “We need to win the European election by turning it into a massive anti-Macron referendum.
“Our task next May is to ensure that the message goes out loud and clear that we need to say ‘stop’ to Mr Macron. We need to win this battle… Our ballots are our bullets,”
Mr Mélenchon, leader of the leftist La France Insoumise (France Unbowed) party, added: “The judicialisation of politics is a strategy used by governments worldwide.” He he described himself as one of the many “victims of political persecution”.
Anti-corruption investigators raided Mr Mélenchon’s home and party headquarters earlier this month as part of a long-running investigation into the alleged misuse of EU Parliament funds to pay party employees.
In a video posted on his Facebook page, he said: “This is a politically-motivated act, it’s an act of political aggression.”
The hardline leftist has since accused the presidency of orchestrating the raids.
National and regional elections across Europe, and most recently in Germany, have seen a surge in support for far-right and green movements, at the expense of the traditional centre-right conservative and centre-left social democrat parties.
And the May vote is expected to follow the same trend, with ‘outsider’ parties tapping into growing disaffection among the mainstream left and right.
Mr Macron has repeatedly framed the European election as a fierce battle between anti-immigrant nationalists and pro-EU progressives and sent emissaries to make contacts with like-minded parties.
But his view on the election has been slammed as “too simplistic” by France’s Socialists, who have accused Mr Macron of dumbing down the debate.
Socialist party spokesman Boris Vallaud told RTL radio on Monday: “We must always fight against illiberal nationalism. Always. But we cannot win this battle by simplifying the debate and identifying just two rival camps: those who are for Europe and those who are against it. I don’t even know what that means.
“Europe must be socialist.”
He added: “Socialist Europe would focus on fighting inequalities and climate change”.