Speaking before a meeting of the Asian Cup organising committee, Hammam said United's tour so close to the July 7-29 tournament was casting a shadow over it.
'(The) organisation of different competitions in and around the AFC Asian Cup is affecting the mood of the competition. The visit of Manchester United is of particular concern to us,' Hammam said.
'The Manchester United tour dates clash with the AFC Asian Cup and AFC doesn't want any competitions to be promoted or organised during the month of July.
'If the tour goes ahead then it will be a breach of the OAA (Organising Association Agreement).'
United are scheduled to play in Malaysia on July 27, just two days before the Asian Cup final in Jakarta. They are also due to make stops in
The AFC and Football Association of Malaysia (FAM) signed an OAA in November, under the terms of which the Malaysians were supposed to ensure the Asian Cup would not be battling for publicity with other football events.
The Asian Cup is being co-hosted by