Al Jazeera's Charles Stratford, reporting from Ashdod, said the Israeli army confirmed intercepting a boat that departed from Europe in order to "violate the legal naval blockade that is imposed on the Gaza Strip".
Israel says its lethal tactics are needed to prevent armed breaches of the Gaza border which, it says, the enclave's Islamist Hamas rulers are encouraging to distract from domestic problems linked to a grinding Israeli-Egyptian blockade on them.
Pierre Stambul, co-president of the French Jewish Union for Peace, told AFP that one of the three vessels in the "Freedom Flotilla", called al-Awda in Arabic (the return), may arrive off Gaza shores as early as Sunday.
Following Al Awda was a Swedish-flagged yacht called Freedom Italy, with 36 activists from 15 different countries, said Zaher Birawi, head of the International Committee for Breaking the Siege of Gaza.
Abu Salima also mentioned that before the attack, the flotilla members did not face any obstacles on their way.
Another Palestinian teen died Saturday from wounds sustained at protests along the border fence separating Israel and Gaza.
Additionally, many attempts have been made throughout the years to draw the public's attention to the on-going siege of Gaza.
The Awda, carrying at least 23 people, was meant to reach the Gaza port approximately at noon local time on Sunday, but was redirected instead to the Israeli port of Ashdod.
He pointed out in a statement that the solidarity activists aboard the ship sailed towards Gaza peacefully and legally.
Four boats left from Scandinavia in mid-May and stopped in some 28 ports along the way, the coalition said.
The two sides normalized relations in June 2016, but their ties sank to a fresh low in May 2018 after the expelling of envoys amid growing tensions over the killing of dozens of Palestinians in the Gaza Strip at the hands of Israeli forces.
One Israeli soldier has been killed in the same time period.
The Gaza health ministry said 154 Palestinians have been killed since the protests began March 30.
Palestinians want to establish a state in the Gaza Strip, the West Bank and East Jerusalem, territories that Israel took control of in the 1967 Middle East war.