It is the antichrist (dajjal) who will shed blood in the End Times. Hazrat Mahdi (as) will come to halt these rivers of bloodshed by the antichrist.

One of the most important pieces of information about Hazrat Mahdi (as) that our Prophet (saas) gives in many of the hadiths is the fact that Hazrat Mahdi (as) will cause no blood to be spilled at any time in his life. Indeed, our Prophet (saas) says of the age under the spiritual leadership of Hazrat Mahdi (as) that "he will not wake a sleeping person or even shed one drop of blood." (Ibn Hajar al-Haythami, Al-Qawl al-Mukhtasar fi `Alamat al-Mahdi al-Muntadhar, p. 29)

Our Prophet (saas) expresses this as follows in another hadith:

In the time of [Hazrat Mahdi (as)] no one will be woken up from their sleep OR HAVE A BLEEDING NOSE. (Ibn Hajar al-Haythami, Al-Qawl al-Mukhtasar fi `Alamat al-Mahdi al-Muntadhar, p. 44)

Not shedding blood is Allah’s command to Hazrat Mahdi (as) by revealing it to our Prophet (saas). It is therefore impossible for Hazrat Mahdi (as) to employ any other means than love, affection, compassion, friendship and brotherhood in causing the moral values of Islam to rule the world.Because any other behavior would mean violating Allah’s commandment, may Allah forbid.

Hazrat Mahdi (as) is a person of love and affection. The intense love and affection that Allah creates in Hazrat Mahdi’s (as) soul and that will have an impact across the whole world are expressed as follows in hadiths:

Due to the blessings of Imam az-Zaman [Hazrat Mahdi (as)] people's hearts will be filled with mutual love and unity. (Bihar al-Anwar, vol. 53, p. 187; Mikyaal al-Makaarem, vol. 1, p. 52)

[In the time of Hazrat Mahdi (as)] LOVE AND KINDNESS WILL PERVADE ALL THE NOOKS AND CORNERS OF THE EARTH. (Iqbaal al-A'maal, p. 507; Bihar al-Anwar, vol. 21, p. 312)

Certain people and circles with ulterior motives who say that blood will be shed in floods in the End Times have ascribed, in their own eyes, such a task to Hazrat Mahdi (as) both out of lack of knowledge of the hadiths and also deliberate distortion, of those hadiths under the influence of satan. It is true that there will be bloodshed in the End Times, but it is the antichrist who will shed it in floods, not Hazrat Mahdi (as). The antichrist means blood and pus. The antichrist will elevate hatred of Muslims to its highest level in the End Times. He will imprison the whole of mankind, and especially the Muslim world, within an oppressive system, the like of which has never been seen before. Our Prophet (saas) also describes this climate that will emerge in the End Times in the hadiths:

(At that time) There will be much corruption, disorder and rebellion, and people will kill one another. People will take their own lives and the world will be filled with sorrow. The accursed dajjal will appear at such a troubled time...(Ash-Sharani, Mukhtasar Tazkirah al-Qurtubi, p. 482)

At a time when the world will be in utter confusion and disorder, when murders and tribulation appears... when roads will be cut, when some attack some others... (Al-Muttaqi al-Hindi, Al-Burhan fi Alamat al-Mahdi Akhir az-Zaman, p. 454)

Allah reveals to our Prophet (saas) that Hazrat Mahdi (as) will not shed blood and our Prophet (saas) imparts this to Hazrat Mahdi (as). Hazrat Mahdi (as) will abide by this command of Allah.

From Mr. Adnan Oktar`s interview on Adıyaman Asu TV on 27 September, 2010

Allah will send Hazrat Mahdi (as) to halt the flow of blood. Hazrat Mahdi (as) is “anti-blood.”It is Hazrat Mahdi (as) who will completely silence Darwinism and materialism, the religion of the movement of the antichrist that incite violence and conflict, cause people to regard one another as animals, and incite selfishness, cruelty and ruthlessness. In doing this he will use science and philosophy and silence the movement of the antichrist with its own weapons.

With the total silencing of the movement of the antichrist, love, affection, compassion, peace, security, brotherhood and friendship will replace conflict, war, fighting and anger. All weapons will be eliminated in the time of Hazrat Mahdi (as), and the money spent on the military will instead be diverted to science, art, technology and other activities that benefit mankind. Our Prophet (as) foretold these delights in the time of Hazrat Mahdi (as) 1400 years ago:

All grudges and mutual hatred will be removed…Earth will be filled with peace, just as a vessel is filled with water;. There will also be unity in religion and none other than Allah will be worshipped anymore. The (competents of) battle will abandon its load (arms and equipment). (Sunan Ibn Majah, 10/334)

(The competents of) War will abandon its load (namely, arms and the like)… All hostility and hatred vanish.(Al-Sharani, Mukhtasar Tazkirah al-Qurtubi, p. 496)