The FBI (search) is conducting interviews of people who may have information about or may be planning violent acts at the Republican National Convention (search), the agency's head of counterterrorism said Wednesday.

Counterterrorism division chief Gary Bald (search) told reporters that people who commit violent acts under the guise of protests at the convention are "domestic terrorists."

"Intelligence indicates that conventions are viable targets for domestic and international terrorists," he said, declining to get into specifics.

News of efforts by police agencies to determine protester activities at the Republican convention has led to charges that law enforcement officials are trying to put a stop to protests. FBI officials deny the charges, and have said they are specifically concerned about individuals with information about possible violence at the conventions, not demonstrators in general.

"We do not monitor rallies. We do not monitor people who go to rallies. But if we have an allegation that someone will commit a violent act, we're going to make sure that doesn't happen," Bald said, rejecting critics' claims that his department is trying to squelch free speech.

Bald said that the questioning conducted so far has been a "measured response" appropriate to information the FBI had received regarding violence at the convention. He added that he has neither the time nor interest in stopping people from exercising their First Amendment (search) rights.

Officials said questioning first started before the Democratic convention, when the FBI reported it had learned information indicating that some individuals may have been planning attacks on news vans.

The Democratic convention in Boston last month saw little disruption from protesters, though many protesters who spoke with FOXNews.com said they were saving their energy for the Republican convention in New York City. The convention starts Aug. 30 and lasts four days.

Counterterrorism agents and federal and local law enforcement officers have tried to interview dozens of people in at least six states about possible violence at either convention, according to news reports. The New York Times reported on Tuesday that FBI officials in Washington have urged field offices around the country in recent weeks to make an extra effort to interview sources and gather information that might help to detect criminal plots.

The initiative was first suggested months ago in FBI bulletins sent to law enforcement officials describing tactics used by demonstrators to disrupt the political conventions. The bulletins advised local police departments to report suspicious activities that may lead to violence at the convention.

The advisory led to an inquiry by the Justice Department's inspector general's office, which asked the Office of Legal Counsel (search) to determine whether the inquiries violated any constitutional issues.

A memo from the Office of Legal Counsel, dated in April, did not find problems with the bulletins, though civil-rights advocates have complained that the instructions are tantamount to harassment of anti-war demonstrators and other protesters.

Fox News' Anna Stolley contributed to this report.