It is not the intent of this ordinance to repeal, abrogate, annul or in any way impair or interfere with existing provisions of other laws or ordinances, except those specifically repealed by this ordinance, or with private agreement, or with restrictive covenants running with the land to which the city is a party. Where this ordinance imposes a greater restriction upon land, buildings or structures than is imposed or required by such existing provisions of law, ordinance, contract or deed, the provisions of this ordinance shall control.