It happened at 09.30 BST on Saturday at the junction of Cheapside and Bridlesmith Gate, blocking both roads.
Police cordoned off the scene but said clearing it was complicated due to overhead power lines. There are no reports of injuries.
Services were suspended between Nottingham Station and Royal Centre until shortly before 13:00 with continued disruption to the timetable.
A nearby branch of Barclays bank was evacuated as a precaution.
A tram and a lorry have collided in Nottingham city centre.