The protesters demanded more action on climate change, while some farmers raised their concerns about a potential European trade deal with the South American bloc Mercosur, which they fear will bring unfair competition to their products.
Macron promised to oppose such a deal unless South American producers follow the same environment and health standards as Europeans. The French president also discussed a plan to be better prepared for drought and use water cautiously.
During his visit to the Paris Agricultural Fair, Macron defended his unpopular pension plan, which includes raising the minimum retirement age from 62 to 64.
Some activists shouted "no to the pension plan" as Macron inaugurated the event, but the French president vowed to go ahead with the reform despite strikes and protests in the country.
Macron said that he came to the fair to support farmers who work hard and have small pensions that the government has substantially improved.
The Paris Agricultural Fair, one of the world’s largest farm fairs, draws crowds every year.