No this is not the case. The Shia Muslims believe that the prophet Mohammad (sawa) who possesses prophethood, messengership and imamah, is the highest of all creation. Anyone saying otherwise is a deviant and ignorant.
In a narration from Al-Kafi, Imam Ali (as) when asked by a Jew if he's a prophet, replied the following:
إنما أنا عبد من عبيد محمد صلى الله عليه وآله
I am only an 'abd (slave) from the slaves of Mohammad (sawa).
'Abd in this context means a servant or slave in the sense of complete obedience and not worship. The Quran also uses the word 'Abd for the non-worship sense too. Check 24:32.
Therefore, despite the unfathomable status of Imam Ali (as), he shows that he is in a lower position as compared to Rasullah (sawa) by expressing his obedience and veneration to him.
So then imagine the status of rasullah when someone such as Ali expresses such a statement!
May Allah grant you success