The Permanent Court of Arbitration in The Hague ruled Monday the Russian government is liable for around $50 billion in damages in the case against Yukos, disbanded in 2006.
Lavrov said after the ruling the Russian government and others involved in the case will use whatever legal means necessary to defend their case.
"The process is not over -- appellations are allowed," he said.
The court at The Hague ruled Moscow has to cover about half of the $114 billion sought in response to a decision by the Kremlin to seize the oil company.
Its former boss, Mikhail Khodorkovsky, was arrested in 2003 and convicted of tax evasion and theft in 2005. The company was then sold off, with most of the shares going toward Russian state-owned oil company Rosneft, controlled by Igor Sechin, a close ally of President Vladimir Putin.
Rosneft itself has been the target of sanctions against Russia's energy sector issued in response to Moscow's stance on crises in Ukraine.