Mr Price said that they should be interpreted as a "colloquial suggestion" that the Conservative leader's attitudes to women and gay people were outdated and disrespectful.
The letter cited previous comments by Mr Craig, including his assertions that gay relationships were "not normal" and that Prime Minister John Key was "too gay" for his Helensville electorate.
Mr Craig said Dr Norman had until Friday at 5pm to issue a public apology and retraction for statements he made at the Big Gay Out.
During his speech, the Greens co-leader said Mr Craig "thinks a woman's place is in the kitchen and a gay man's place is in the closet".
Greens' lawyer said that Mr Craig had failed to understand that the legal threshold was higher for defaming a politician.
He said that if Mr Craig wished to pursue the matter further, he should preserve any evidence of comments made about women or gay people, including emails, that could be relevant in the discovery phase.
Mr Craig, a millionaire property manager, has sought and received retractions and apologies from media organisations, individuals and a satirical news website for comments made about him.