(CNN) -- San Francisco's new sheriff is facing misdemeanor charges over an alleged domestic abuse incident on New Year's Eve, authorities said.
Sheriff Ross Mirkarimi, who was sworn in Monday, said Friday he will not resign.
"We are cooperating with law enforcement and the district attorney's office and will, of course, continue to do so," he told reporters.
The charges were announced by San Francisco District Attorney George Gascon, who also took office Monday.
Mirkarimi is accused of domestic violence with battery, child endangerment and dissuading a witness.
Gascon said there were a series of text messages between the sheriff and his wife, Eliana Lopez, the alleged victim, about the incident.
Lopez, standing next to her husband, called the charges "unbelievable" and said the couple would fight them.
"I don't have any complaint against my husband," Lopez said. "We are together. ... this is completely wrong."
Mirkarimi was booked and released on bail, San Francisco police said.
Mayor Edwin M. Lee called the charges "extremely serious and troubling."
"As elected officials, our primary responsibility and focus must always be to fulfill our duties to the people of San Francisco," Lee said in a statement.
He said he would review options under the city charter, but "ensure that we do not take steps that undermine the integrity of the criminal justice proceedings under way."