"The government has brought thousands of people from all over the country to show it is still popular among the poor population, but also to show that Colom is not going anywhere soon," Al Jazeera's Teresa Bo, reporting from Guatemala City, said.
There have been several protests both for and against the president since the accusations were made earlier in the week.
The president has denied any role in the death of Rodrigo Rosenberg, who was shot dead last week while riding his bicycle in the capital.
A video distributed at the lawyer's funeral showed him blaming his death on Colom and Gustavo Alejos, the chief of the cabinet.
"Those who know me they know I am incapable of ordering a murder," Colom told Al Jazeera on Friday.
"I don't know the motives Rodigro Rosenberg had to film that tape but if you see those who were involved in filming the tape you understand who they are ... they are destabilisers."
The US Federal Bureau of Investigation (FBI) has been asked to aid an investigation into Rosenberg's death, along with the International Commission Against Impunity in Guatemala (CICIG), a United Nations panel set up in 2007 to clean up corruption in the Central American nation.
In Rosenberg's video, which was later posted on the Youtube website, he said officials might want to kill him because he represented a businessman who was murdered after Colom allegedly invited him to enter into acts of corruption.
|Rosenberg was shot dead while riding his bicycle in Guatemala City
Khalil Musa, who purportedly declined the invitation, was shot dead on April 15 in Guatemala, along with his daughter.
Colom told Al Jazeera he had no intention of stepping down over the matter.
"The people of Guatemala has the right to protest and ask for justice ... but be careful of crossing the line," he said.
"Accusing a president of murder publicly could be sedition, [it] is sedition if they cannot prove it. It's not against me, Alvaro Colom, they are accusing the constitutional president of the republic of a crime in which they have no proof."
Colom's election victory in 2007 gave Guatemala its first left-leaning leader since Jacobo Arbenz was thrown out of office in 1954 by a coup orchestrated by the US Central Intelligence Agency (CIA).