About a dozen tractors rolled into the capital Paris on Thursday morning with banners saying "No to Mercosur."
"We said we would come to Paris and here we are," says Ludovic Ducloux, from one of the organizations behind the protest, to the AFP news agency.
EU member states are expected to give the go-ahead to the comprehensive trade agreement at ambassadorial level on Friday, despite opposition from countries including France, Poland and Hungary.
European Commission President Ursula von der Leyen will then travel to Paraguay early next week for a formal signing.
