Amid a tight police deployment, the demonstrators gathered at a stadium on Friday with the intention of staying there until their demands were met.
Photo taken with a mobile phone by a citizen journalist. It is on the ground reporting that is keeping information flowing from this small but determined country.
But the demonstration escalated into clashes after dusk, as authorities used batons and tear gas against stone-throwing protesters.
Guelleh has served two terms and faces an election in April, but critics are concerned by changes he made to the constitution last year that scrapped a two-term limit.
Officials from the Union for Democratic Change, an umbrella group of three opposition parties, gave speeches at Friday's demonstration calling for Guelleh to step down.
The group's leader, Ismael Guedi Hared, told the AFP news agency before the demonstration that Guelleh should leave power and called for a sustained protest movement.
"For the moment, our goal is to remove Ismael Omar Guelleh from power," he said.