Related Rule
United States of America
Practice relating to Rule 66. Non-Hostile Contacts between the Parties to the Conflict
Section D. Refusal to receive parlementaires
The US Field Manual (1956) provides: “The commander to whom a parlementaire is sent is not in all cases obliged to receive him.” 
United States, Field Manual 27-10, The Law of Land Warfare, US Department of the Army, 18 July 1956, as modified by Change No. 1, 15 July 1976, § 463.
The manual adds:
The present rule is that a belligerent may not declare beforehand, even for a specified period – except in case of reprisal for abuses of the flag of truce – that he will not receive parlementaires. An unnecessary repetition of visits need not be allowed. 
United States, Field Manual 27-10, The Law of Land Warfare, US Department of the Army, 18 July 1956, as modified by Change No. 1, 15 July 1976, § 464.