I venture to believe that this angel was not the Almighty angel of the covenant, but only some ordinary servant in token of God's displeasure. See Exodus 33:2.
Related Commentaries of Exodus 32:34
Exodus 32:34
34 Therefore now go, lead the people unto the place of which I have spoken unto thee: behold, mine Angel shall go before thee: nevertheless in the day when I visit I will visit their sin upon them.