Hi @Arun Kumar ,
Thanks for using Microsoft Q&A !!
Sorry but you cannot use the Cassandra db connector for Azure Cassandra API. Also, at this time there is no connectors available for Cosmos DB Cassendra API and so I suggest you to please post this as a feedback at Azure Data Factory UserVoice. This will allow the community to upvote and for the product team to include into their plans.
Thanks
Saurabh
----------
Please do not forget to "Accept the answer" wherever the information provided helps you to help others in the community.