All the incidents involved took place outside of Gaza before the current war.
Israel took corrective action in four units, giving “additional information” on the fifth, the department says.
This means all the units remain eligible for US military assistance.
Washington is Israel’s major military backer, supplying it with $3.8bn (£3bn) worth of weapons and defence systems per year.
The announcement is the first determination of its kind for any Israeli unit by the US government.
State Department spokesman Vedant Patel said five security forces units committed gross violations of human rights.
“Four of these units have effectively remediated these violations, which is what we expect partners to do,” he said.
“For a remaining unit, we continue to be in consultations and engagements with the government of Israel; they have submitted additional information as it pertains to that unit,” he added.
The department denies claims it backed down under political pressure by continuing military assistance to the unit despite being unable to say whether or not there had been any accountability in the case.
