Lavrov’s an idiot. He has it exactly backwards; by using civilians and hostages as shields, the terrorists have placed themselves outside international humanitarian law and have forfeited their right to any protection under those laws.
4th Geneva Convention Relative to the Protection of Civilian Persons in Time of War, Part 3, Article 1, Section 28:
"The presence of a protected person (aka civilian noncombatant) may not be used to render certain points or areas immune from military operations."