Bismillah, if any sane person would be asked what war was worse, he certainly would answer that war against prophet (salallahu alaihi wa ala alihi wa sallam).
Below we would like to present shia hadith with SOUND CHAIN, on this. When people disputed near Imam of shias Abu Jafar about this, they differ, some of them said that war against Ali is worse than war against prophet (sallalahu alaihi wa ala alihi wa sallam), others said that war against prophet was worse.
However shia Imam allegedly said:
حرب علي أشر من حرب رسول الله صلى الله عليه وآله
War against Ali worse than war against prophet – sallalahu alaihi wa sallam.
When he was asked how is that, he answered:
إن حرب رسول الله صلى الله عليه
وآله لم يقروا بالاسلام وإن حرب علي ( عليه السلام ) أقروا بالاسلام ثم جحدوهThose who fought against prophet (sallalahu alaihi wa sallam) didn’t accept Islam, and those who fought against Ali (alaihi salam) accepted Islam and then rejected it.
Chain of this hadith was authenticated by shaykh of shias Husayn ar-Radhy at his official site.
Comments:
1) In accordance to this report, Aisha, Talha, Zubayr, Muawiyah and others were disbelievers. And this is faith of shias, faith of their forefathers.
2) Mushriks which fought against prophet (sallalahu alaihi wa ala alihi wa sallam) better than companions which fought against Ali.
gift2shias.com 
Yes it is correct because unbeliever of Mecca who fought with prophet were ‘Kafir’ and the companion who fought with Ali were ‘Munafiq’ and Allah will keep the Minafiq in the bottom most part of the Hell as said in Holy Quran . And all of us know well that a friend sitting besides you with knife in his hand to kill you out of jealousy whenever he get the time is more dangerous than the enemy who is standing against you.
Alhamdolillah