Pope Francis called on Sunday for an "immediate" end to Israeli strikes on the Gaza Strip, and for the resumption of dialogue for the release of hostages and a "definitive ceasefire".

"I am saddened by the resumption of the intense Israeli bombardment of the Gaza Strip, with so many deaths and injuries", Francis wrote in his Angelus prayer, which was published Sunday as the 88-year-old was being discharged from more than five weeks in hospital.

"I ask that the weapons be silenced immediately and that the courage be found to resume dialogue so that all the hostages can be freed and a definitive ceasefire reached", said Francis, who was set to return to the Vatican on Sunday.

"The humanitarian situation in the Gaza Strip is once again very serious and requires the urgent commitment of the conflicting parties and the international community", he said.

Earlier, Pope Francis greeted and thanked the faithful from a balcony of Rome's Gemelli hospital on Sunday, the first time the 88-year-old has been seen in public since his admission on February 14.

"Thank you, everyone", a weak-sounding Francis said into a microphone, as he sat in a wheelchair waving gently to hundreds of people gathered below, and doing the occasional thumbs-up sign.

"I can see that woman with yellow flowers, well done", he said with a small smile, to laughter from the crowd.

The head of the world's 1.4 billion Catholics, who has spent over five weeks in hospital battling pneumonia, was on the balcony for two minutes then was discharged immediately. (AFP)