The boat's female passengers sought to break the 10-year Israeli blockade of the Gaza Strip.
Israeli naval forces intercepted a flotilla seeking to break Israel's 10-year blockade on the Gaza Strip on Wednesday when it was just a few dozen kilometres from the coast, Israeli media sources reported.
The Zaytouna-Oliva flotilla, which departed from Barcelona in September, was carrying 13 activists from Norway, Sweden, Australia, Egypt, Tunisia, Malaysia, Israel, the US and Canada. A Nobel peace laureate Mairead Maguire was also among them.
No injuries have been reported as the activists did not resist when they were taken over and redirected to the Ashdod port.
In a statement, the Israeli Defense Forces (IDF) said the visit and search of the vessel was "uneventful."
"In accordance with international law, the Israeli Navy advised the vessel numerous times to change course prior to the action."
"Following their refusal the Navy visited and searched the vessel in international waters in order to prevent their intended breach of the lawful maritime blockade of the Gaza Strip," the IDF added.
The Gaza Strip is home to around two million Palestinians and has been described as the "world's largest open air prison."
The United Nations has called for the blockade to be lifted, but Israel maintains the blockade to prevent materials it believes Palestinians could use for military purposes from entering the enclave.
The activists had expected to be stopped by Israeli authorities at around 100 nautical miles from the Gazan coast.
But Gazans, gathered on the beaches to welcome the boat, became hopeful when the activists announced that they had passed the fatal line of 100 miles and everything was going well.
The move was immediately condemned by the Palestinian Liberation Organisation.
"The Palestinian cause for freedom and independence is a universal quest for justice embraced by millions worldwide," PLO Secretary General Saeb Erekat said in a statement.
"The flotilla is a humble yet significant reminder that it is time to turn statements into concrete actions," he added.
Meanwhile, people took to social media demanding the release of the activists.
In January, another Gaza-bound boat Marienne was intercepted. It was carrying 20 activists including an Israeli lawmaker Basel Ghattas and former Tunisian President Moncef Marzouki.
In 2010, one such move turned to tragedy when Israeli troops intercepted Turkish aid flotilla Mavi Marmara, and killed 10 activists.