Iran urged "restraint" from both Russia and Ukraine on Tuesday while blaming the United States and NATO for the sharp escalation of tensions.
President Vladimir Putin announced late Monday that Russia recognised the independence of Ukraine's separatist-held Donetsk and Lugansk regions, paving the way for the deployment of Russian troops.
Moscow's move triggered international condemnation and a promise of targeted sanctions from the United States and the European Union.
"The Islamic Republic of Iran calls on all parties to exercise restraint and avoid any action that could aggravate tensions," a foreign ministry statement said.
Ministry spokesman Said Khatibzadeh added that "unfortunately, the interventions and provocative actions of NATO and mainly the US have complicated the situation in the region.
"We are following the issues related to this country with sensitivity."
Tehran and Washington have been bitter foes since the 1979 Islamic revolution toppled the US-backed monarch and Iranian students took more than 50 US embassy staff hostage for over a year.
Both are now engaged in efforts to revive the 2015 deal that offered Iran sanctions relief in return for curbs on its nuclear programme, after then US president Donald Trump unilaterally withdrew from it in 2018.