"We are alarmed that along with the adequate reaction from the UN Security Council and the collective reaction of the international community, unilateral action is being taken around North Korea that involves increased military activity," Russian Foreign Minister Sergei Lavrov told reporters.
He was speaking after holding talks with his Ukrainian counterpart Leonid Kozhara.
Without pointing out any specific country, Lavrov urged all sides involved in the Korean standoff to refrain from muscle-flexing.
This appeared to be a reference to the recent flare-up in tensions between Pyongyang and Washington in the wake of joint US-South Korean military exercises close to the border.
South Korea and the US began annual large-scale military exercises March 11. The drills involve 10,000 South Korean and 3,500 US troops.
Prior to the exercises, Pyongyang threatened the US with a pre-emptive nuclear strike amid warnings that it plans to terminate the Korean War Armistice Agreement.
It warned of retaliatory countermeasures if the US and South Korea went ahead with the drills.
The US Thursday dispatched two nuclear-capable B-2 stealth bombers on an "extended deterrence" practice run over South Korea.
US officials said the exercise should serve "to demonstrate very clearly the resolve of the United States to deter against aggression on the Korean Peninsula".
North Korea responded Friday by placing its strategic rocket forces on standby to strike US and South Korean targets.