Answer:
President Monroe said this because the United States wanted to establish a policy of non-interference in the internal affairs of European nations. This policy, known as the Monroe Doctrine, was intended to prevent European powers from interfering in the affairs of newly independent nations in the Americas. By stating that the United States would not interfere in the internal concerns of any European power, Monroe was signaling that the United States expected the same respect for its own sovereignty and independence. The Monroe Doctrine became a cornerstone of American foreign policy and helped to establish the United States as a major power in the Western Hemisphere.