"The United States of America is the most successful of nations," Bush said. "Historically, where immigration is concerned, we're also the most welcoming of nations. And these two facts are related."
Bush's remarks come days after Trump vetoed a congressional resolution disapproving of his declaration of a national emergency at the US-Mexico border.
At the event during which he issued the veto, Trump appeared in the Oval Office, flanked by supportive sheriffs and families of Americans killed by undocumented immigrants. He has repeatedly warned about caravans of migrants headed toward the U.S. and has argued that there is a crisis at the border, including in a tweet ahead of his veto in which he claimed that a border wall will "help stop Crime, Human Trafficking, and Drugs entering our Country."
Bush, by contrast, struck a welcoming tone in his speech, applauding the new citizens and remarking that those who seek to begin a new life in the US often "bring a special love of freedom, because they have seen how life works without it."
"You paid America the high tribute of aspiring to live here, leaving behind familiar ways and places and accepting a process that everyone knows is not easy," Bush said. "Our country in return honoured your efforts and soon will be honored to call you a citizen."
His remarks drew praise from Congressman Colin Allred, D, who shared a clip from Bush's speech on Twitter.
"Common sense immigration reform shouldn't be a partisan issue," Allred said in the tweet. "Thank you to #TX32 resident President George W. Bush for speaking out on the value immigrants provide to our nation. Congress must work together on comprehensive reform and fix this broken system."