The defendants were arrested over clashes that happened in late October while they were escorting Sonko to the western town of Mbour, and in which government supporters were hurt.
"We will get together to see if we will appeal" the judgment, said their lawyer Abdoulaye Tall, who added they were also ordered to pay a fine of 50,000 CFA francs (about $75 / euros).
One of the pro-government supporters was sentenced to two months in prison over the clashes.
The authorities have denied any misuse of state institutions in the legal proceedings against Sonko, who came third in the last presidential election in 2019 and plans to run again in 2024.
This is not the only legal trouble connected to Sonko, who was accused last year of raping an employee of a beauty salon where he was getting a massage.
His arrest and indictment in March 2021 led to several days of deadly riots in Senegal, a nation usually viewed as a beacon of stability in politically volatile West Africa.
When he appeared in a Dakar court over the accusations for the first time early in November, one of his lawyers called the case a state "conspiracy" that should be dropped.
The authorities have denied any misuse of state institutions in the legal proceedings against Sonko, who came third in the last presidential election in 2019 and plans to run again in 2024.
He was elected mayor of the southern city of Ziguinchor in January and has enjoyed a rapid political rise in part thanks to his popularity with young people.
But critics characterize him as a populist firebrand. He regularly tears into social elites and corruption, slamming the economic and political grip of multinational firms and former colonial power France.