The Imperial Household Agency said the decision was because Emperor Akihito had developed a fever last week and is still recovering.
Akihito turns 83 years old on Friday. Plans for his birthday celebration have not been changed.
Akihito had invited Prime Minister Shinzo Abe and other top officials for today's banquet.
Akihito expressed an apparent wish to abdicate in a rare public address in August, citing concerns that his age and health conditions may start limiting his ability to fulfil official duties.
A government-commissioned panel of experts is discussing a possibility of setting up a special law to accommodate his abdication, without touching more controversial issues, including a possibility of allowing a female emperor.