BEIJING—China’s President Xi Jinping pledged $60 billion in financing for Africa’s development and waived some debt owed by the continent’s poorest countries, batting away criticism that Chinese investments may be exacerbating a looming African debt crisis.

Speaking Monday to dozens of African leaders at a Beijing summit, Mr. Xi portrayed China as a responsible power, working with African countries in pursuing economic development, reducing poverty and combating regional security threats.

China...