They cited an unnamed government spokesman saying Friday's strike was an "intolerable act of aggression against a sovereign state".
The strikes followed Wednesday's suspected chemical attack on a rebel-held Syrian town which killed 89.
North Korea has carried out tests to develop a nuclear missile.
The UN has banned it from missile or nuclear tests.
But it has repeatedly broken those sanctions. It has successfully tested nuclear bombs of increasing power and claims to have been able to make warheads small enough to fit on a missile, but some experts have cast doubt on those claims.
On Friday, US missiles struck a Syrian airbase, killing at least six people. It was the first US attack on a Syrian government facility, although the country had previously targeted the Islamic State group in the region.
"The US missile attack against Syria is a clear and intolerable act of aggression against a sovereign state and we strongly condemn it," a government official in North Korea said, as quoted by the KCNA news agency.
"The reality of today shows that we must stand against power with power and it proves a million times over that our decision to strengthen our nuclear deterrence has been the right choice.
"Only military power of our own will protect us from imperialistic aggression.
"We will keep bolstering our self-defensive military might in various ways in order to cope with the ever-intensifying US acts of aggression."

About 1,000 athletes, aged between 14 and 18, will participate in the event, scheduled for 27 July to 1 August.
Boxers Carl Frampton and Michael Conlan, and swimmer Sycerika McMahon are among Northern Irish athletes to have previously competed at the Games.
NI Commonwealth Games chairman Robert McVeigh described it as a hugely significant day for local sport.
"This is the result of many years of lobbying and hard work," said McVeigh.
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"It offers a great opportunity for children to strive towards being part of the largest ever Team NI at a Commonwealth Youth Games."
More than 60 nations were represented at the last Youth Games, staged in Samoa in September, with Northern Ireland finishing eighth in the medal table.
The next Youth Games will take place in the Bahamas in 2017, after which it will revert to a four-year cycle.
The formal announcement of Northern Ireland's hosting of the 2021 Games will take place at Belfast City Hall on Monday, with Commonwealth Games NI patron Dame Mary Peters in attendance.
It is expected the swimming competition will take place at the Aurora complex in Bangor, with the Mary Peters Track in Belfast hosting the athletics, and the gymnastics being held in Lisburn.
Northern Ireland were the only bidders for the 2021 Games, after Jersey and Botswana withdrew.
North Korea says a US missile strike on Syria "proves a million times over" that it was right to strengthen its nuclear programme, state media report.
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Northern Ireland has been chosen to host the Commonwealth Youth Games in the summer of 2021.