The 84-year-old Briton talked to a farmers' leader in front of a plastic cow in the fan village at the Spa circuit and then chugged from a litre of milk -- jokingly pretending to faint as he did so.
A police spokesman said the farmers had agreed not to stage a more serious protest, such as blocking access roads, in return for being allowed to make a symbolic gesture and meet Ecclestone.
Ecclestone said he had not been worried by that: "They wouldn't block the roads," he told reporters when asked about the threat, also expressing sympathy with the farmers' grievance.
Dairy farmers in Belgium have burned tyres and blocked roads with tractors in the past to protest against tumbling prices triggered by a global surplus and shrinking demand from China and the halting of exports to Russia.
Europe's milk market was liberalised in April with the removal of 30-year-old quotas, creating expansion opportunities for some dairy farmers while threatening the livelihood of others.
A European Union council of farm ministers is due to meet on Sept. 7, with more action by farmers expected that day.
(Reporting by Alan Baldwin, editing by Amlan Chakraborty)
