The comments were Pyongyang's first since US President Donald Trump ordered the strikes on an air base in the war-wracked country Thursday in retaliation for an apparent chemical attack.
"The US missile attack against Syria is a clear and intolerable act of aggression against a sovereign state and we strongly condemn it," KCNA news agency quoted an unnamed spokesman for the North Korean foreign ministry as saying.
Analysts had earlier said the strikes contained a clear message for Pyongyang that the US was not afraid to exercise the military option, and there had been speculation as to how the North would respond.
Trump has recently threatened unilateral action against Pyongyang if Beijing fails to help curb its neighbour's nuclear weapons programme.
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However, Pyongyang's response suggested the reclusive state was determined to continue with its nuclear weapons programme.
"The Syria attack thoroughly reminds us the fact that it is absolutely dangerous to have any illusions about imperialism and only military power of our own will protect us from imperialistic aggression," he added.
"We will keep bolstering our self-defensive military might in various ways in order to cope with the ever-intensifying US acts of aggression."
The North has carried out five nuclear tests - two of them last year - and expert satellite imagery analysis suggests it could well be preparing for a sixth.