Tajik President Emomali Rahman told Russian President Vladimir Putin in a telephone conversation that "terrorists have no nationality."
Earlier, Russian media reported that all four attackers who killed 133 people in Moscow on Friday were citizens of Tajikistan.
Rahman strongly condemned the "cruel and bloody attack" and said that "terrorists have neither nationality, nor homeland, nor religion," the Tajik presidency said.
Russia announced on Saturday that it had arrested 11 people, including four of the direct attackers, and that they were all foreign nationals.
The jihadist organization Islamic State (IS) claimed responsibility for the attack.
"At this moment of national mourning in Russia, the head of state of Tajikistan emphasized the solidarity of all citizens of Tajikistan with the Russian people," the press service of the Tajik presidency announced.
Bonus video:
