TEHRAN — The first anniversary of Iran’s disputed presidential election passed largely without violence on Saturday, as protesters generally stayed off the streets amid a heavy presence of the riot police. There were reports of sporadic clashes between the police and protesters around the city, including a large group of students at Tehran University. Demonstrators also showed up along many parts of Enghelab, or Revolution, Street, one of Tehran’s longest thoroughfares, and a small group of protesters gathered on Jomhouri Avenue near the Hafez Bridge. Reports of arrests varied. Deputy Police Chief Ahmad-Reza Radan said “only a small number” of people were taken into custody in Tehran. But the Human Rights Activist News Agency said that at least 200 people were arrested, with many loaded into vans and taken away. Police and security officials made clear in the days leading up to the anniversary of the disputed election that they would not tolerate any protests.