Donald Trump says he wants to "suspend immigration from areas of the world where there is a proven history of terrorism."
It wasn't immediately clear whether Trump was proposing a change from his long-standing proposal to temporarily bar foreign Muslims entering the U.S.
The presumptive GOP presidential nominee also called on Muslims in the U.S. to work with law enforcement on finding potential attackers.
He made the proposal Monday in Manchester, New Hampshire, a day after the worst mass shooting in U.S. history in Orlando. He called for an overhaul of the nation's immigration system and said that "we have to control our borders now - not later, now."
During his speech, Trump also claimed that the gunman in the Orlando shooting was an Afghanistan native - even though the suspect was born in New York City.
He said the gunman, who has been identified as Omar Mateen, was "born an Afghan." The shooter was born in Queens to parents who emigrated from Afghanistan.
It's possible Trump misspoke. The false claim that Mateen was born in Afghanistan is not included in Trump's prepared remarks distributed by the campaign during Monday's speech
Trump was originally scheduled to speak out against Hillary Clinton but changed the focus of the speech after the shootings. His speech did include several pointed references to his Democratic opponent, however.
He repeatedly criticized Clinton's immigration plan, her attempts to tighten the nation's gun control laws and for not using the phrase "radical Islamic terrorism" when describing recent attackers.
Trump also said national intelligence officers are "not being allowed to do their jobs" due to restrictions imposed upon them by President Barack Obama's administration.
He had also planned to hold fundraisers in Boston and New Hampshire, and a rally at 6 p.m. in Portsmouth, New Hampshire, but cancelled them due to the shootings.