Thousands of Qataris and expatriates rallied at the site of Saturday's bombing near a British school, claimed by an unknown group.
According to AFP, French embassy sources said a team of experts had arrived in Doha to help in the investigation.
The group calling itself "Jund al-Sham," (Soldiers of the Levant), has claimed responsibility for the attack, in a statement on an Islamist website.
"No to terrorism," "Progress and security, whether the cowards like it or not," read some of the banners raised by the demonstrators.
Sons of Emir Sheikh Hamad bin Khalifa al-Thani, government ministers, Muslim clerics and other prominent figures participated in the rally.
