The demonstrations in Munich began on Friday evening with about 150 protesters. Those numbers swelled to 3,500 on Saturday, according to police, when a large anti-war demonstration took place.
Organisers of the "Action Alliance Against the NATO Security Conference" said around 6,000 people participated.
All in all, police said they were "very satisfied" with the security situation over the weekend. One police officer was slightly injured.
Police said that although the presence of big groups of far-left demonstrators indicated "a real possibility that violence would be used," a strong police presence ensured that demonstrations remained largely peaceful.
Around 3,700 security forces were stationed in Munich's downtown area for the duration of the conference.