Americans should be vigilant of politically-motivated violence spurred by harsh rhetoric, House Speaker Nancy Pelosi (D-Calif.) warned Thursday.

Pelosi, referencing the assassination of gay rights activist and San Francisco Supervisor Harvey Milk in 1978, said Americans must "curb our enthusiasm" in some political debates.

"I have concerns about some of the language that is being used because I saw this myself in the late '70s in San Francisco, this kind of rhetoric was very frightening and it created a climate in which violence took place," Pelosi said.

"And so I wish that we would all, again, curb our enthusiasm in some of the statements that are made, understanding that some of the people -- the ears it is falling on are not as balanced as the person making the statement might assume," the speaker cautioned.

The Department of Homeland Security (DHS) controversially released a memo earlier this year warning of domestic terrorism from "right-wing extremists," and a small spate of violence related to politics have popped up this year.

Pelosi said that leaders who cause any "incitement" to violence must take responsibility for their words.

"Our country is great because people can say what they think and they believe, but I also think that they have to take responsibility for any incitement that they may cause," she said.