What is the reference for the verse He is the one who rules over the whole world with an iron rod?
The biblical references for these are not in the present tense, but "future." They refer to the coming Kingdom of God and Jesus' rule on the earth over the nations... along with the joint-rulership of His saints who shall wield the same power:
"Ask of Me, and I shall give thee the heathen for thine inheritance, and the uttermost parts of the earth for thy possession. Thou shalt break them with a rod of iron; thou shalt dash them to pieces like a potter's vessel. Be wise now therefore, O ye kings: be instructed, ye judges of the earth. Serve the Lord with fear, and rejoice with trembling. Kiss the Son, lest He be angry, and ye perish from the way, when His wrath is kindled but a little. Blessed are all they that put their trust in Him." (Ps.2:8-12)
"...and she brought forth a man child, who was to rule all nations with a rod of iron: and her Child was caught up unto God, and to His throne..." (Rev.12:5)
"...with righteousness shall He judge the poor, and reprove with equity for the meek of the earth: and He shall smite the earth: with the rod of His mouth, and with the breath of His lips shall He slay the wicked..." (Isa.11:4)
"...I will cause you to pass under the rod, and I will bring you into the bond of the covenant: and I will purge out from among you the rebels, and them that transgress against Me: I will bring them forth out of the country where they sojourn, and they shall not enter into the land of Israel: and ye shall know that I am the Lord." (Ezek.20:37-38)
"...What will ye? Shall I come unto you with a rod, or in love, and in the spirit of meekness?" (I Cor.4:21)
"...he that overcometh, and keepeth My works unto the end, to him will I give power over the nation: and he shall rule them with a rod of iron; as the vessels of a potter shall they be broken to shivers: even as I received of My Father." (Rev.2:26-27)
"...the Spirit itself beareth witness with our spirit, that we are the children of God: and if children, then heirs, heirs of God, and joint-heirs with Christ; if so be that we suffer with Him, that we may be also glorified together." (Rom.8:16-17)
"...out of His mouth goeth a sharp sword, that with it He should smite the nations: and He shall rule them with a rod of iron: and He treadeth the winepress of the fierceness and wrath of Almighty God..." (Rev.19:15)
Jesus isn't ruling the whole world with a rod of iron, yet. The prophecy is still ahead of us.