"But what government? A government that doesn't even have the right to enter or leave [the Palestinian territories] without Israeli permission."
He said: "The leadership of Hamas government has committed an aggression against the rights of the Islamic nation by accepting what it called ... respecting international agreements.
"I am sorry to have to offer the Islamic nation my condolences for the [virtual demise] of the Hamas leadership as it has fallen in the quagmire of surrender."
But Hamas's Osama noted that the Mecca agreement was supported by most of the respected leaders in the Muslim world and would not be undermined by a comment from anyone who was not aware of all the facts and political developments.
"If anyone wishes to express reservations on the Mecca agreement, we respect that but at the same time we affirm that Hamas would never accept to be dealt with as if the movement is not rational and needs guidance from someone."
"Hamas has managed to withstand an unfair blockade for a year now. This blockade on Hamas could have been lifted if Hamas agreed to recognise the Zionist entity [Israel], but Hamas will never recognise Israel," he added.
Hamas, which came to power in January 2006, refuses to recognise Israel - a stance which has led to Western countries boycotting the Hamas-led Palestinian government after its electoral win in January 2005.