"This is outrageous. This is a grave punishment," Genrikh Padva said adding that such a punishment could be administered only for very serious violations.
Media reports say the Federal Penitentiary Service intended to transfer Khodorkovsky to a solitary cell to ensure his safety.
Khodorkovsky, currently serving an eight-year prison term for tax evasion and fraud in a penal colony in eastern Siberia, had his nose slashed Friday by a fellow inmate named Kuchma.
Several stitches were applied to the wound, but doctors ruled against taking him to the hospital because the injury was not sufficiently serious.
Khodorkovsky's lawyer Natalia Terekhova said her client would not press criminal charges against his attacker, who has been transferred to another block.
However, the Penitentiary Service said Khodorkovsky would be transferred Wednesday not to a solitary confinement cell, but to a separate cell, until the situation stabilizes.
