The flailing French president has pledged to counter "social dumping” in France in which companies employ cheaper labour from the poorer eastern European states, threatening French workers’ jobs, an official said.
EU states are divided on rules under which, for example, a Bulgarian truck driver or a Lithuanian bricklayer can work in France for a limited time for the eastern European wage, often below the minimum level guaranteed in wealthy western Europe.
Poland, Hungary, Slovakia and the Czech Republic say they should be allowed to compete on lower prices - just as more developed western EU nations compete on quality products and know-how - to catch up after decades of communist stagnation.
The dispute is shaping up as one of the most contentious issues facing the bloc, exacerbating an east-west rift as it seeks unity to tackle Brexit.
The French official said Emmanuel Macron would seek stricter rules on "social dumping" during his August 23-25 trip to Austria, Romania and Bulgaria, when he would also hold talks with the Czech Republic and Slovakian prime ministers.
The official described the visit as "an important symbol, since these are countries which in the past have been neglected, or ignored by France, or at the very least they feel as if this has been the case”.
Mr Macron pledged during his presidential campaign to reform French labour laws to kick-start the revitalisation of the French economy.
At the moment, France's labour law comprises of 3,324 pages regulating all aspects of the work structure from firings to health and security.
Trade unions in the country have been resisting reform of the code for years in fears of a deterioration of workers' rights.
The country is well-known for its 35-hour working week, introduced under a Socialist government in the 1990s, which results in two-hour lunches and workers often only going into the office four days a week.
If companies want their employees to work more than 35-hours they have to pay between 10 and 50 per cent extra per hour.
The culture is slowly changing, with Mr Macron’s predecessor François Hollande last January giving employers the right to renegotiate longer hours and lower overtime pay with staff.
However, the changes have been fiercely opposed by trade unions and the left wing of the the previous governing Socialist Party, with early 2016 marred by nearly two months of uninterrupted mass protests against the proposals.
Mr Macron’s victory in May with his newly formed centrist En Marche party marked a change in mood in France, however commentators are now concerned he is not going through with his promise to give employers more negotiating powers with workers.
Investment expert Jonathan Fenby, told CNBC last night: "This labour law is absolutely essential to Macron. If he doesn't get that through, he is a busted flush in lots of ways. He's gotta get that through.
"Hollande backed off very largely, Macron's gotta stick with it."