The British-flagged yacht Madleen, operated by the pro-Palestinian Freedom Flotilla Coalition (FFC), left Sicily on Friday and had hoped to reach Gaza later in the day, when the interception occurred, the group said on its Telegram account early on Monday.
Among those on board the boat are Swedish climate activist Greta Thunberg and Rima Hassan, a French member of the European Parliament.
The Israeli Foreign Ministry posted a video on X showing the Israeli Navy communicating with the Madleen over a loudspeaker, urging it to change course.
It later posted a statement saying the "selfie yacht" of the "celebrities" was "safely making its way to the shores of Israel".
"The passengers are expected to return to their home countries."
"While Greta and others attempted to stage a media provocation whose sole purpose was to gain publicity - and which included less than a single truckload of aid," it said.
More than 1200 aid trucks had entered Gaza from Israel within the past two weeks, and the Gaza Humanitarian Foundation had distributed close to 11 million meals to civilians in Gaza, it said.
"There are ways to deliver aid to the Gaza Strip - they do not involve Instagram selfies. The tiny amount of aid that was on the yacht and not consumed by the "celebrities" will be transferred to Gaza through real humanitarian channels," it said.
"The maritime zone off the coast of Gaza is closed to naval traffic as part of a legal naval blockade," a soldier said.
"If you wish to deliver humanitarian aid to the Gaza Strip, you are able to do so through the (Israeli) port of Ashdod."
The yacht, with its 12-person crew, was carrying a symbolic shipment of humanitarian aid, including rice and baby formula.
Israeli Defence Minister Israel Katz ordered the military on Sunday to prevent the Madleen from reaching Gaza, calling the mission a propaganda effort in support of Hamas.
Israel imposed a naval blockade on the coastal enclave after Hamas took control of Gaza in 2007.
The blockade has remained in place through multiple conflicts, including the current war, which began after a Hamas-led assault on southern Israel on October 7, 2023, that killed more than 1200 people, according to an Israeli tally.
Gaza's health ministry says over 54,000 Palestinians have been killed since the start of Israel's military campaign. The United Nations has warned that most of Gaza's more than 2 million residents are facing famine.
The Israeli government says the blockade is essential to prevent weapons from reaching Hamas.
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