Income received from the rental of furnished property is subject to tax according to the rules of ordinary law. As a landlord, you have an obligation to report this income to the tax authorities.
If your tax domicile is in France, you are liable to tax in France on all your income, including the remuneration of your activity abroad.
If your tax domicile is outside France, you are taxable on your income from French sources, unless otherwise stipulated in the tax treaty signed between France and the country in which you reside.

More information on Legislation and Taxation in France: