Peter MacKay, Canada's foreign affairs minister, made the appeal on Thursday against a backdrop of continued Islamist insurgency.
He said: "Canada and our Nato allies have a fundamental national security interest in ensuring that Afghanistan cannot again become a haven or a source for global terrorists.
"We will do our part in Afghanistan and we expect others to do their part."
MacKay later clarified who he was referring to: "Clearly, I'm talking to Nato countries that are currently there, some of whom have restrictions placed on them by their own governments.
"Those forces, we believe, can be deployed to the south," he said. "We'll continue to apply that reasonable plea for burden-sharing in the south."
MacKay said 2,300 Canadian troops based in Afghanistan's most volatile Kandahar region faced "stubborn insurgent forces" that have stalled reconstruction efforts in Afghanistan.
Development initiatives in Helmand, Kandahar, Zabul, Nimroz and Uruzgan provinces have slowed because they are "most unstable at the moment," a senior official said last week.
"These provinces are where insurgencies are most active. You will see national programs reach right across the country in some cases. But in others, security does not permit that.".
Earlier on Thursday, a suicide bomber killed several civilians, including two children, and a British soldier in an attack on a Nato convoy in southern Afghanistan, witnesses and officials said.
Witnesses and an army officer said a suicide bomber threw himself at Nato troops in the main bazaar of Lashkar Gah, the capital of Helmand province.
"The bomber was on foot and hurled himself at the convoy of Nato," said Shamsuddin, an Afghan army officer near the scene.
Afghan security forces and Nato
soldiers face an elusive enemy
Yusuf Ahmadi, a spokesperson for the Taliban, claimed responsibility for the attack and told Aljazeera that at least 14 people died in the attack, including seven British soldiers.
A spokeswoman for the British defence ministry confirmed that several British soldiers had been injured but said "we have no report of British fatalities".
British troops make up the bulk of Nato forces in Helmand, a Taliban stronghold and the heart of the illegal opium industry in the world's biggest producer.
Ghulam Muhiddin, the spokesman for Helmand's governor, said the attacker targeted the vehicle of a British aid organisation.