SAN FRANCISCO (Reuters) - New San Francisco Sheriff Ross Mirkarimi faces domestic abuse charges less than a week after taking office, officials said.

Mirkarimi is charged with misdemeanor counts of domestic violence battery, child endangerment and dissuading a witness, according to the San Francisco District Attorney's Office.

The charges stem from an alleged incident on New Year's Eve with his wife, Eliana Lopez, a former Venezuelan TV actress. She

told reporters last week that she was not pressing charges and objected to the cases against her husband. The couple have a 2-year-old son.

"Regardless of whether the victim supports a prosecution, it is the state's and my office's obligation to ensure the safety of the victim," District Attorney George Gascon said in a written statement.

Mirkarimi, 50, was sworn in on January 8 as the first new sheriff San Francisco has seen in three decades. He narrowly won an open race in November after incumbent Sheriff Michael Hennessey announced his retirement.

The investigation had already begun when he took office. Charges were filed on Friday.

In remarks to reporters outside City Hall on Friday, Mirkarimi said the charges were "very unfounded." Lopez called the case "unbelievable."

Mirkarimi is a Chicago native who has lived in San Francisco for 27 years, according to his campaign website. He was elected to the county's board of supervisors in 2004 and was a district attorney investigator in San Francisco for nine years.

(With reporting by Emmett Berg in San Francisco and Karen Brooks in Austin. Writing by Karen Brooks.)

(Reporting By Ian Simpson)