Tuesday's order came as security officials in the coalition government said there was a conspiracy by officials close to the old administration to spread chaos and take back power.
The interim government was put in place after Zine al-Abidine Ben Ali, the Tunisian president, fled to Saudi Arabia.
After days of gunfights and looting immediately after Ben Ali was pushed out, it had seemed security was being restored but since last week violence has flared again, raising new questions about Tunisia's stability.
Some members of the caretaker government of Mohamed Ghannouchi, the new prime minister, have accused Ben Ali loyalists of fomenting unrest against the new leadership in an attempt to derail the transition to democracy.
The government banned on Sunday the former governing party, the Constitutional Democratic Assembly, and on Monday parliament approved a law granting decree powers to Fouad Mebazaa, the interim president.
The military has for weeks been in the streets helping keep order and filling the gap left by a police force whose ranks have been thinned by desertions and absenteeism.
"The defence ministry has called on retired members of the army, navy and air force ... to go to the regional centres of conscription and mobilisation nearest to their place of residence," said a ministry statement reported by the official TAP news agency.
Tunisia's uprising against Ben Ali's authoritarian rule inspired protest movements elsewhere in the Arab world, notably in Egypt, and its halting progress towards stability is being watched closely in the region.
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