"The Ministry of Defense categorically rejects any claims that use of the Harris tactical radio is unsafe," the ministry said in a statement, pointing out that the encrypted system was used throughout the Baltic states, Poland and the US for secure communications.
"Their reliability has been repeatedly tested not only in joint military exercises, but also in operations," the ministry added, describing claims that the system was unsafe or could be hacked by Russia were "misleading".
The ministry called on media outlets as well as anonymous posters on social media sites "to prevent the spread of misleading information."
US manufacturer Harris Corporation has delivered more than 160,000 communications units to the US, Nato, and other allied forces worldwide.
In 2007, Latvia placed a $3.3m order with Harris for tactical radios and is believed to be pondering another order as part of its plans to beef up its defense capability in the wake of Russia's aggression in Ukraine.