Oscar-winning film director Pedro Almodóvar also put his name to the letter in which prominent figures from the arts world called for the European Union to "condemn the bombing by land, sea and air against the Palestinian civilian population in the Gaza Strip".
They echoed UN Security Council calls for demanded an immediate cease fire by the Israeli military, and said Israel must "end the blockade, which the Gaza Strip has suffered for over a decade".
"Gaza is experiencing horror these days, besieged and attacked by land, sea and air. The homes of Palestinians are being destroyed, they are being denied water, electricity [and] free movement to their hospitals, schools and fields while the international community does nothing," the art professionals said.
They called on Israel to open the borders to allow medical teams and food supplies into the Gaza Strip.
Israel and Palestine must "enter into dialogue" to ensure a "just and lasting peace" to the conflict," the letter's authors added.
Over 1,200 Palestinians have died in the 23-day conflict, with at least 19 people killed when a UN school was bombed in the early hours of Wednesday morning.
Javier Bardem and Penélope Cruz and started dating other in 2007 and married in 2010. The two became an item after co-starring in the Woody Allen comedy Vicky, Cristina, Barcelona.
Bardem is regularly involved in political activism and has campaigned against controversial Spanish plans to drill for oil and gas of Spain's Canary Islands.
He also sparked a diplomatic row in 2013 when he let slip the private remarks of a French diplomat about that country's relationship with Morocco.
He claimed that the ambassador had described Morocco as, "A mistress with whom we sleep every night, even if we are not particularly in love, but whom we must defend. In other words, we turn a blind eye."