"It just never ends", he said of global terror threats after a gunman opened fire near the Franklin Roosevelt subway station.
The unidentified attacker attempted to run away while continuing to shoot at other officers and injured two more, Brandet confirmed to the BBC. The armed man was so killed.
White House press secretary Sean Spicer said just before the news conference began that Trump had been briefed on the shooting that happened while he was meeting with the Italian prime minister.
Trump did not comment on the shooting at the top of his remarks but said after he was asked for a reaction, 'It looks like another terrorist attack, and what can you say?
"We have to be strong and we have to be vigilant and I've been saying this for a very long time", he added.
Armed police were deployed to the landmark after the shooting.
The latest incident came just three days after a tense first round of elections for a new French President.
ISIS has claimed credit for the attack. Reuters reported that police are now searching the suspect's home east of Paris and have issued an arrest warrant for a second suspect who authorities believe may have been involved in the shooting.
The identity of the attacker wasn't immediately known, but Paris police said he targeted police officers along the high-profile Champs-Elysees shopping district.