Hi Utkarsh,
Offers are used to generate propositions against a specific dimension, by default Recipient.
Hence, there is no standard/direct way of embedding offers in a Transactional email.
Implementation experts (Campaign Developers) may have a way out by customizing Message Center execution instance, if at all that is feasible.
I would suggest to reach out to your Contact at adobe (CSM/AM or Consulting Team) to seek assistance if that can be taken up as a project.
Hope that helps.