No streets or alleys, except those laid down on such plat and bearing the approval of the Platting Commissioner, as hereinbefore provided, shall subsequently in any way be accepted as public streets, or alleys, nor shall any public funds be expended in the repair or improvement of streets and alleys subsequently laid out and not on such plat. This restriction shall not apply to a street or alley laid out by the City, nor to streets, alleys or public grounds laid out on a plat by or with the approval of the Platting Commissioner.