"Women... Are completely forbidden from showing their eyes," said the statement, which the Syrian Observatory for Human Rights said was distributed in IS-controlled areas of Deir Ezzor province in the east.
Women are also forbidden from wearing "open abayas (traditional black gowns) that reveal colourful clothes worn underneath", it said.
Abayas, it added, "must not be decorated with beads, sequins or anything else" and women "must not wear high heels".
"Anyone who violates this will be penalised," it added, without elaborating on the punishment.
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The group has been accused of committing some of the worst atrocities in Syria's more than three-year war, including mass kidnappings and summary executions.
In parts of Deir Ezzor city that are under jihadist control, the group also distributed a statement forbidding the sale and public use of nargileh (water pipe) tobacco and cigarettes, the Observatory said.
"In its effort to implement Islamic law and to fight evil things, it is completely forbidden to sell cigarettes and nargileh anywhere," it said, citing the jihadists who also forbade "smoking in public".
It has taken over large swathes of formerly opposition-held areas, after fighting rebels seeking President Bashar al-Assad's overthrow.
In recent weeks, it has fought on multiple fronts against regime troops, rebels including Islamists, and Kurdish fighters.