By Shannon Stapleton NEW YORK (Reuters) -Pro-Palestinian protesters blocked several New York City bridges and a tunnel on Monday to demand an immediate ceasefire in the three-month-old Israel-Hamas conflict before police arrested hundreds of them and reopened the roadways. Dozens of chanting demonstrators sat at entrances to the Brooklyn, Manhattan and Williamsburg bridges across the East River, as well as at the Holland Tunnel connecting New York City with New Jersey across the Hudson River, local media reported. Police arrested 325 demonstrators, a New York Police Department spokesperson sai…