Tarantino said he would not "waste time" by responding to the criticism, Italy news agency, ANSA, reported Thursday.
Tarantino was in Rome for the European premiere of his latest film -- about an American slave who teams up with a bounty hunter to rescue his wife.
"Django Unchained" was inspired by a 1960s spaghetti western of the same name.
Lee posted on Twitter last week that he would not watch the film because it would be "disrespectful to my ancestors."
"American Slavery Was Not A Sergio Leone Spaghetti Western. It Was A Holocaust. My Ancestors Are Slaves. Stolen From Africa. I Will Honor Them," he wrote.
Italian actor Franco Nero, who played the title role in the 1966 "Django" and has a cameo in "Django Unchained," said both movies are "political," ANSA reported.
Tarantino is "one of the few complete-total directors that exist, like [Woody] Allen, Oliver Stone and Paul Mazursky," Nero said. "It is a pleasure to work with him, but he wants perfection."