The Israeli Navy on Saturday intercepted a ship with pro-Palestinian activists as it tried to reach Gaza in breach of the Israeli blockade.
No one was hurt when navy forces boarded the Estelle en route to the Gaza Strip, the Israeli military said.
The Finnish-flagged aid boat Estelle was forced to dock in the Israeli port city of Ashdod.
There were between 19 and 30 people on board, according to different sources. The cargo was said to include cement and medical supplies.
Israel imposed the blockade when Hamas took control of the area in 2007.
A recent UN report warned that conditions in Gaza have so deteriorated that it will no longer be "a livable place" by 2020.