The four men, all in their early 20s, were taken into custody after raids at properties across the city. Armed police were present at one of the raids, but no shots were fired, police said.
“These arrests and searches are part of an ongoing investigation into Islamist related terrorism,” the statement said. “A number of residential addresses and vehicles are being searched by specialist officers in west and central London as part of the investigation.”
No further details were available.
British police arrested 11 people last month in other Islamist-related operations. It was not immediately clear if the various investigations were connected.
In August, Britain raised its international threat level to the second-highest classification of “severe”, meaning an attack was considered highly likely. British Prime Minister David Cameron has said Islamic State militants battling for territory in Syria and Iraq also posed a grave security risk to Britain-Reuters