needs $20 million to keep operations going in December.
"We had to reduce the food rations since we upscaled our food assistance from 850,000 to reach 1.5 million people in September," said Abeer Etefa, a spokeswoman for the food agency, on Tuesday.
"We were not fully funded for the increase in the number of people so we had to make some tough choices in reducing some complementary food to be able to reach more people," she told AFP.
The amount of reductions vary each month and also depend on the district.
"We hope to get the necessary funding as we are expanding the operation for another six months so we will see more cuts if we don't get the necessary funding," Etefa added.
Syria's 20-month-old civil war has now spread to nearly every part of the country and activists say it has left more than 40,000 dead.
The UN says humanitarian conditions in Syria are "catastrophic," with four million people likely to need some kind of aid by January. More than 460,000 people are already living in camps outside Syria.
The WFP estimates it needs 15,000 tonnes of food a month for 1.5 million people which costs about $22 million. The agency is aiming to increase deliveries in the new year and says it needs $134 million for January to June, said another agency spokeswoman Bettina Luescher.
When fully functioning, the WFP was able to give a monthly food basket including rice, bulgur, vegetable oil, sugar, dried and canned food, pasta and salt.
Some food items such as tomato paste, canned fish, and supplementary foods such as tea, were cut from the food rations and could only be added "if we ensure adequate funding," Etefa said.
On top of the financial crisis, the agency has also had to cut back deliveries, which are carried out through the Syrian Red Crescent, because of difficulties getting food to the country and the growing intensity of the war.