He said, "I am only a Messenger of your Lord who says 'I shall bestow upon you the gift of a son endowed with a spotless character.'" (Tasreef with (3:45) is very important here)
He said: "Don’t be afraid, I am merely a messenger from your Lord to tell you about the gift of a holy son."
Dr. Munir Munshey
He said, "What I am, is a messenger of your Lord to bestow upon you a pious son."
Dr. Kamal Omar
(The angel) said: “Certainly, what (is the fact is that) I am a messenger from your Nourisher-Sustainer, so that I may bestow on you (on His behalf) a righteous son.”
The angel replied: “Relax, I am a Messenger from your Lord. I am sent to inform you that you are going to have a righteous son as a gift (in response to your devotion to God.
Faridul Haque
He said, "I am indeed one sent by your Lord; so that I may give you a chaste son."
Hasan Al-Fatih Qaribullah
'I am the Messenger of your Lord, ' he replied, 'and have come to give you a pure boy.
(The Spirit) said, “I am the Rasul of your Rabb! I have been disclosed to grant you a pure son.”
Sayyed Abbas Sadr-Ameli
He (the angel) said: 'Verily I am only a messenger of your Lord that I bestow on you a pure son'
Al-muntakhab fi tafsir al-Qur'an al-Karim
The disguised angel said: "But I am the Messenger of Allah, your Creator", I am assigned to grace you with the divine prerogative of procreating a son who is stamped with the character of sublimity, holiness and piety"