Gutierrez said Kelly, a retired four-star Marine general, is "a politician, OK, not a general."
"What could be more mean and more vicious than to say 'you've got six months to pack up...and leave the United States'?" Gutierrez asked of Kelly.
He said that the retired officer "did nothing" when Trump impugned Vietnam War veteran Sen. John McCain (R-Ariz.) last year, saying he preferred soldiers who "weren't captured."
Gutierrez previously called Kelly a "disgrace to the uniform" and a "hypocrite" for siding with "white supremacists enabling the president's actions" on DACA.
Kelly responded, saying "empty barrels make the most noise."
"[Congressmen] have the luxury of saying what they want as they do nothing and have almost no responsibility," Kelly, who served for decades and lost a son in Afghanistan, said.
Watch more on Gutierrez' initial criticism above.