The command to fight the people until they say "La ilaha illallah Muhammad Rasul-Allah", and establish Salat, and pay the Zakat, and believe in everything that the prophet (ﷺ) brought. Whoever does that, his life and his wealth are protected except by its right, and his secrets are entrusted to Allah, the most high. Fighting those who withhold Zakat or other than that is one of the duties of Islam and the Imam should be concerned with the Laws of Islam
وَحَدَّثَنَا سُوَيْدُ بْنُ سَعِيدٍ، وَابْنُ أَبِي عُمَرَ، قَالاَ حَدَّثَنَا مَرْوَانُ، - يَعْنِيَانِ الْفَزَارِيَّ - عَنْ أَبِي مَالِكٍ، عَنْ أَبِيهِ، قَالَ سَمِعْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ " مَنْ قَالَ لاَ إِلَهَ إِلاَّ اللَّهُ وَكَفَرَ بِمَا يُعْبَدُ مِنْ دُونِ اللَّهِ حَرُمَ مَالُهُ وَدَمُهُ وَحِسَابُهُ عَلَى اللَّهِ " .
It Is narrated on the authority of Abu Malik: I heard the Messenger of Allah (ﷺ) say: He who professed that there is no god but Allah and made a denial of everything which the people worship beside Allah, his property and blood became inviolable, an their affairs rest with Allah.