The development comes after the Queen underwent tests in hospital last week and cancelled a two-day trip to Northern Ireland.
But the head of state has the "firm intention" of leading the nation in honouring the country's war dead on Remembrance Sunday on November 14.
In a statement, Buckingham Palace said: "Following on from their recent advice that the Queen should rest for a few days, Her Majesty's doctors have advised that she should continue to rest for at least the next two weeks.
"The doctors have advised that Her Majesty can continue to undertake light, desk-based duties during this time, including some virtual audiences, but not to undertake any official visits.
"Her Majesty regrets that this means she will be unable to attend the Festival of Remembrance on Saturday, November 13.
"However, it remains The Queen's firm intention to be present for the National Service of Remembrance on Remembrance Sunday, on November 14."