Oklahoma City National Memorial Act Amendments of 2003 - Amends the Oklahoma City National Memorial Act of 1997 to give responsibility for administration of the Memorial to the Oklahoma City National Memorial Foundation (currently administered by the Oklahoma City National Memorial Trust).
Requires the Trust to transfer specified Memorial property, rights, authorities, and duties to the Foundation. Dissolves the Trust.
Authorizes the Secretary of the Interior, acting through the National Park Service (NPS), to enter into cooperative agreements with the Foundation for the NPS to provide interpretive services related to the Memorial at NPS expense.
Requires the Secretary to reimburse the Foundation for funds obligated or expended for interpretive services, security, and other costs and services related to the Memorial prior to enactment of this Act to the extent that funds are made available.