WASHINGTON—President Barack Obama assured American Indians on Thursday that they have a place in his White House and on his agenda, telling tribal leaders their marginalized community deserves more from its government.

Obama opened a conference that drew leaders from 386 tribal nations—the first meeting of its kind in 15 years.

It comes as American Indians remain entrenched in a class-action lawsuit against the federal government, claiming the government has long swindled them out of land royalties.

Obama said he didn’t blame tribal leaders for skepticism about another politician offering hopeful words. But he said he has no interest in going through the motions of just holding a summit with them.