Israel has stepped up security at Tel Aviv airport ahead of the expected arrival of hundreds of pro-Palestinian activists.
The move dubbed the “flytilla” comes as Greek authorities prevent a flotilla from sailing for Gaza to challenge the Israeli blockade.
Immigration and airport officials have been told to “act with determination” in deciding whether to allow people in.
Israeli police spokesman Micky Rosenfeld said:
“Those who will be coming in quietly without causing any provocative incidents or possibility of public disturbances or even violence at the airport, will be allowed to come through. At the same time those, as far as we are concerned, in terms of security, have been arrested in the past will not be allowed to come in.”
Israel has vowed to stop vessels trying to breach its blockade of Gaza.
It is a year since Israeli commandos killed nine Turkish activists from another flotilla.
Hamas is now directing its anger at Greece.
“We call on Greece to allow the departure of the Freedom Flotilla which has a noble humanitarian goal, and that is the breaking of the illegal siege,” Hamas official Mahmoud Al-Zahar told supporters.
Greece says it imposed the ban due to fears for the activists’ safety.
Pro-Palestinian campaigners say those trying to fly in are peaceful and are not heading for Gaza but the West Bank on a trip that has been planned for months.