The decision on Tuesday came after staffers had demonstrated in December when colleagues who wore skirts deemed too short were barred from entering the building.
The staffers said that security guards at Israel's parliament, the Knesset, had started to strictly enforce rules on the length of skirts without giving a reason.
The committee was subsequently formed to examine the issue.
"It was agreed that the dress code would remain in place. At the same time it was decided to create an enforcement mechanism including issuing warnings before denial of entry to the building," a Knesset statement said.
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Haaretz newspaper said on Wednesday that staff would initially get two warnings about inappropriate dress and would only be denied entry if there was a third occasion.
"Arrival at the Knesset should be in proper and dignified attire," the statement added.
"One should not arrive in clothing which does not show respect for the Knesset, such as T-shirts, crop-tops, shorts, sandals, short dresses or skirts, tracksuits."
It said that shirts bearing political slogans were also banned.
Haaretz said that the code did not specify what is an appropriate skirt length, but the committee ruled that miniskirts were forbidden.