It is unlawful for any person knowingly or wilfully to resist, oppose or obstruct the chief of police, any other policeman, the municipal judge, or any other officer or employee of the city in the discharge of his official duties; or, by threats or otherwise, to intimidate or attempt to intimidate any such officer or employee from the discharge of his official duties; or to assault, beat, revile, abuse, be disrespectful to, or use abusive or indecent language toward or about, any such officer or employee while such officer or employee is in the discharge of his official duties. (Prior code § 422)