The spokesman, Ismail Radwan, said a long-term agreement "will kill the resistance, which is the Palestinian people's legitimate right as long as the occupation continues to exist."
Radwan spoke after Egyptian officials, including Foreign Minister Ahmed Aboul Gheit, announced Cairo was preparing to proceed to the next step in truce talks between Hamas and Israel, attempting to render it a long term agreement.
Hamas official Ayman Taha told reporters in Cairo that his delegation was briefed by the Egyptians on an Israeli proposal for a year-and-a-half long truce with only partial opening of the border, which they rejected.
Hamas countered the proposal with one including a year-long truce and the opening of all border crossings, which Taha said must now be discussed with leaders in Damascus.
The issue of new system to monitor the border crossings is key to preserving the cease-fire, and Israel, the United States and Egypt are trying to work out security arrangements to ensure Hamas does not smuggle weapons into the strip before any opening.
'We began to return what we'd lost'
Taha told journalists after the talks that the Islamist group was open to Turkish observers being part of the monitoring system, alongside the Europeans stipulated in a 2005 agreement on the border crossings.
That agreement, supported by Egypt and Israel, also stated that the borders should be controlled by members of Palestinian Prime Minister Mahmoud Abbas' presidential guard.
Radwan's response was a restatement of a speech by Hamas representative in Lebanon, Osama Hamdan, who said the Palestinian organizations were justified in smuggling arms into Gaza.
"No one has the right to prevent the Palestinians from equipping themselves with weapons as long as the occupation continues," he said.
Hamdan added that the organizations had already launched their rearmament immediately upon the declaration of a short-term ceasefire, and said Palestinians in the West Bank should do the same.
"From the first day of the ceasefire we began to return what we'd lost and to improve what we have in our hands," Hamdan said. "No ships, planes, or technology and satellite imagery will prevent the weapons smuggling."
He said the smuggling required "a lot of sacrifice and martyrs and people lost," but that weapons were arriving and would "continue to arrive".