"The laws governing our immigration system are not working," Bush said at a ceremony in which 20 people became U.S. citizens, The Dallas Morning News reported.
Noting the country's "immigration heritage has enriched America's history," Bush said the current debate about immigration reform is "good" because "the system is broken."
Bush unsuccessfully promoted immigration reform during his eight years in office and promised during his presentation not to engage in partisan politics.
He called for a "benevolent spirit" in ongoing congressional wrangling over a proposed immigration reform bill.
America is "a nation of laws, and we must enforce the laws," he said, adding, "America can be a lawful society and a welcoming society at the same time."