"I did not hear this expression. If it was said then of course this is unacceptable," Putin told foreign news agency journalists here.
"I think he himself understands that. He is an educated man... This is unroyal behaviour," Putin said.
Prince Charles stoked controversy during a visit to Canada earlier this week by reportedly comparing the recent actions of Putin to those of Hitler.
Russia angrily reacted to the comments and demanded an official explanation from Britain.
Russia said the comments were "not worthy of a future British monarch".
Charles, 65, made the comments during a trip to a museum in Canada, in a private conversation with a Polish-born woman who had fled the Nazis as a child.
"If these words were really said, then undoubtedly they are not worthy of a future British monarch," foreign ministry spokesman Alexander Lukashevich had said in Moscow.
"We have requested an official explanation from British authorities over the statements," he said.