Protesters scaled part of the Liver Building in Liverpool as part of a demonstration against tuna fishing.
Greenpeace said it was highlighting "destructive fishing methods" used to catch the tuna sold by Princes Foods, which is based in the building.
A handful of protesters climbed on top of the building's portico to drape a banner. About 20 others, dressed as sharks, held placards.
Officers attended and Princes described the protest as "disappointing".
A Merseyside Police spokesman described it as a peaceful protest and said no offences had been committed.
Greenpeace said it was urging Princes to stop selling tuna caught by a method described as "purse seining with fads".
It claimed the practice, which involves surrounding tuna with a huge net, also attracts and catches thousands of sharks as well as other marine life.
David Ritter, head of the Greenpeace oceans campaign, said: "Princes is the biggest tuna company in the country, responsible for more than one in three tuna tins sold in Britain.
"But killed alongside Princes tuna is almost the entire cast list of Finding Nemo, and this includes rare sharks as well as other important animals facing extinction in the wild."
A spokesperson for Princes said: "We have been in ongoing discussions with Greenpeace and recently requested a further meeting to discuss a number of additional sustainability commitments we have recently made.
"It's disappointing that they have chosen to take this action ahead of listening to what we have to say."
The protest, which began on Monday morning, had ended by the afternoon.
- 21 February 2011
- 8 February 2011