First off, it's not PIRACY, Micko...the Israel Navy are not civilians robbing a boat. Your terminology is fucked, but I'm not fucked (an expression you so love to proffer...reflects your mindset I guess). Second, the Blockade is legal and the use of Blockade in International Waters is also legal. Here's the "rules", at least according to the US version. Put that in YOUR crooked little pipe and smoke it:

1. A MILITARY BLOCKADE IS LEGAL: "The belligerent right of blockade is intended to prevent vessels and aircraft, regardless of their cargo, from crossing an established and publicized cordon separating the enemy from international waters and/or airspace." The Commander's Handbook on the Law Of Naval Operations, Section 7.7.1. (U.S. Department of Defense, July 1, 2007)

2. A MILITARY BLOCKADE CAN BE ENFORCED IN INTERNATIONAL WATERS: "Attempted breach of blockade occurs from the time a vessel or aircraft leaves a port or airfield with the intention of evading the blockade, and for vessels exiting the blockaded area, continues until the voyage is completed." The Commander's Handbook on the Law Of Naval Operations, Section 7.7.4. (U.S. Department of Defense, July 1, 2007)

3. A BLOCKADE IS LEGAL EVEN IF TRANSPORTING HUMANITARIAN AID: "Neutral vessels and aircraft engaged in the carriage of qualifying relief supplies for the civilian population and the sick and wounded should be authorized to pass through the blockade cordon, subject to the right of the blockading force to prescribe the technical arrangements, including search, under which passage is permitted." The Commander's Handbook on the Law Of Naval Operations, Section 7.7.3. (U.S. Department of Defense, July 1, 2007)

4. IS IT LEGAL TO BOARD SHIPS AND CAPTURE THOSE ABOARD WHILE ENFORCING A BLOCKADE? "Neutral merchant vessels and civil aircraft are liable to capture by belligerent warships and military aircraft if engaged in any of the following activities: Resisting visit and search; Carrying contraband; Breaching or attempting to breach blockade; Violating regulations established by a belligerent within the immediate area of naval operations. Neutral vessels or aircraft attempting to resist proper capture lay themselves open to forcible measures by belligerent warships and military aircraft and assume all risk of resulting damage." The Commander's Handbook on the Law Of Naval Operations, Section 7.7.10. (U.S. Department of Defense, July 1, 2007.