The benchmark palm oil contract for August delivery on the Bursa Malaysia Derivatives Exchange closed 0.7pc lower at 2,069 ringgit ($493.91) per tonne at the end of the trading day.
The market is up 2.8pc this week, but charted a fourth straight monthly decline with a 1.2pc drop on-month.
"Crude oil and soyoil prices fell, and export gains are also reducing," said a futures trader in Kuala Lumpur, as palm oil prices are impacted by movements in related commodities.
"Even though end-stocks in May are going to be lower (than April), the market is looking at the reducing growth in demand."
Malaysian palm oil exports also rose 6.5-10.2pc on a monthly basis in May, according to data from cargo surveyors Societe Generale de Surveillance, Intertek Testing Services and AmSpec Agri Malaysia on Friday.
Oil fell on Friday and held on track for its biggest monthly drop in six months as comments from US President Donald Trump ramped up trade tensions, weighing on the demand outlook.
Meanwhile, the Chicago July soybean oil contract declined 0.7pc after four earlier sessions of gains. Soybean prices are set to finish May on a positive note for the first time in four months.
In other related oils, the September soyoil contract on the Dalian Commodity Exchange slipped 0.4pc and the Dalian September palm oil contract eased 0.3pc .
Palm oil prices are affected by movements in soyoil, with which it competes for global market share.