The pictures surfaced a day after the army commander told President Robert Mugabe to stop purges of ruling party officials liked to former Vice-President Emmerson Mnangagwa.
The troops, believed to be from Inkomo Barracks on the outskirts of Harare, were heavily armed.
Some pictures showed the tanks blocking a major road leading to the capital, sparking fears of a possible mutiny.
Other tanks were parked by the roadside. There were no reports of violence, but the situation in the capital was tense.
The movements by soldiers occurred hours after Zanu-PF youths told journalists in Harare that they were ready to die for President Robert Mugabe following army commander Constantino Chiwenga’s unprecedented statement.
Gen Chiwenga, an ally of ousted Mr Mnangagwa, said squabbling over President Mugabe’s succession now posed a security threat and the army may be forced to intervene.
Zanu-PF secretary for youths Kudzai Chipanga said they were ready to defend the ageing leader against the army, further stoking fears of unrest.
“We as the Zanu-PF youth league are a lion which has awakened and found its voice,” he said.
“Therefore, we will not sit idly and fold our hands whilst cheap pot shots and threats are made against the legitimate and popularly elected leader of the revolutionary party Zanu-PF and Zimbabwe.”
Mr Chipanga said soldiers should stop meddling in Zanu-PF affairs.
“All those in security sector fatigues who wish to engage in politics are free to throw their hats in the ring and not hide behind the barrel of the gun,” he added.
“We wish to remind them that conniving and conspiring to overthrow a constitutionally elected government is a crime in this country and anywhere in the world.”
Defence minister Sidney Sekeremayi was not available for comment.
The majority of Zimbabwe’s army commanders are veterans of the country’s liberation war and were heavily involved in the ruling party politics.
President Mugabe has in the past complained about the military’s meddling in politics and his wife Grace recently claimed some commanders were threatening a coup if Mr Mnangagwa was not allowed to succeed her husband.
The 93-year-old fired his deputy a week ago after accusing him of deceit and disloyalty.
Mr Mnangagwa escaped to South Africa, but issued a statement promising to return in the next few weeks to take over power.
Mr Nyathi is Africa Review’s correspondent in Zimbabwe