Hello @harshada p Thank you for your question. From the List channel messages documentation, the only Odata query parameter currently supported is $top - there isn't yet a way to get only the mention messages using Graph API. You can filter the data on your end once the response is received. Would you also consider filing a feature request on the M365 developer platform so we can look into this?
Let me know if this helps and if you have further questions,
Diana.