Berlin's Police President Margarete Koppers told the state parliament interior committee that police discovered at least three bombs on May Day, each with an estimated blast radius of 15 – 20 metres.
They were found in several places along the demo's route, and police are working on the assumption that they were intended for use against riot officers.
Experts are currently inspecting the 40-centimetre pipes-bombs to see if they were functional. Koppers said they were home-made explosives which could have injured several people.
"In future operations we have to be prepared for people who have a blind hatred inside them," said Koppers.
Some radical leftists had called for violent attacks against the police in the run-up to Berlin's traditional anti-capitalist protests on May Day. The demonstration, which drew some 10,000 participants, erupted into violence part way along its route, and was dispersed by police after stones and bottles were thrown at them.
Organizers accused the police of using "extreme brutality" to quell the protesters.
It remains unclear whether the pipe-bomb discovery had any connection with an arson attack on two officers in a police car on Saturday night.
Several unknown people attacked the car as it was standing at a traffic light, smashing its back window. One of them tore open a door and threw a flare inside, setting fire to the back seat. The officers, suffered shock, but remained uninjured.
The Berlin domestic intelligence agency said on Friday that there was less violence this May Day that and despite an increase in demonstrators, the far-left scene was struggling to recruit new militants.