One year since the blast, caused by a huge quantity of ammonium nitrate kept at the port for years, no senior official has been held to account, infuriating many Lebanese.
Eight people were wounded in the protest, the Red Cross said.
One of the biggest non-nuclear explosions ever recorded, the blast killed more than 200 people, wounded thousands and was felt in Cyprus, more than 240 km (150 miles) away.
At the time of the explosion, Lebanese were already facing deepening hardship due to the financial crisis caused by decades of state corruption and waste.
The meltdown worsened throughout the last year with the governing elite failing to establish a new cabinet to start tackling the crisis even as poverty has soared and medicines and fuel have run out.