In case of protest against any such change, amendment, supplement, modification or repeal signed by the owners of 33 1/3% or more, either of the area of the lots included in such proposed change, amendment, supplement, modification or repeal, or of those immediately adjacent in the rear thereof extending 100 feet therefrom, or of those directly opposite thereto extending 100 feet from the street frontage of such opposite lots, such amendments shall not become effective except by the favorable vote of 2/3 of all members of Council.