Officers did not observe any visible physical injuries but the woman did complain of pain in her arm. She declined medical attention.
Police said Omenihu was cooperative with officers and was served with an emergency protective restraining order.
The 25-year-old Omenihu is in his second season with the 49ers and part of their defensive line rotation.
He had a career-high 4 1/2 sacks in the regular season and added two sacks and a forced fumble in a wild-card win over Seattle on Jan. 14.
Omenihu played 15 defensive snaps in a win Sunday over Dallas. He injured his oblique during the game but was able to return. He is listed as day to day this week before the NFC title game on Sunday at Philadelphia.
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