"We reject today… and will reject in the future," Meshaal said about a ceasefire, while meeting with journalists in Doha.
Among other demands, the armed Palestinian group of Hamas insists on Israel lifting the siege against the Palestinian enclave, which has lasted for eight years, before it would agree to a ceasefire.
"We will not accept any initiative that does not lift the blockade on our people and that does not respect their sacrifices," Meshaal was quoted as saying by AFP.
"Let us agree on achieving our demands and we will then agree on the zero-hour for a ceasefire," he said.
Israel launched its Operation Protective Edge on July 8, with the alleged objective to prevent Hamas militants from firing rockets from Gaza. At least 31 Israelis have been killed in the past 15 days of the Israeli ground offensive.
A number of major Russian, US and European airlines said they suspended flights to Israel after a missile landed close to Ben Gurion airport outside Tel Aviv earlier this week.
In a phone conversation with Israeli Prime Minister Benjamin Netanyahu on Wednesday, Russian President Vladimir Putin offered help to mediate a truce between Hamas and Israel, including in the framework of the United Nations, according to the Kremlin.