GAZA, May 7 (Reuters) - Gaza's Islamist rulers Hamas on Saturday broke up a Salafist protest against the killing of al Qaeda leader Osama bin Laden in a US raid in Pakistan this week.

Dozens of Salafists -- conservative Islamists who have clashed with Hamas -- gathered in Gaza City's main square holding up posters of bin Laden and chanting We warn you America, we warn you Europe.

Some banners read We are all your soldiers Osama and Osama is alive inside us.

Hamas police forces cordoned off the square, stopped protesters from marching through the streets and ordered them to leave.

Hamas's head in Gaza Ismail Haniyeh had denounced bin Laden's killing as an assassination of an Arab holy warrior.

Analysts said he was trying to cool tensions with Salafist groups who consider Hamas too moderate and call for a fundamentalist version of Islam based on the faith followed by its founders.

Hamas and Salafist groups have been caught up in gun battles in recent weeks.

Hamas, classified by the United States and the European Union as a terrorist group over its violence against Israel, signed a unity deal this week in Cairo with Palestinian President Mahmoud Abbas's more secular Fatah movement.

(Reporting by Nidal al-Mughrabi; Writing by Maayan Lubell; Editing by Andrew Heavens)