Demonstrators also painted their faces with messages of "downgrade Zuma, not South Africa", referring to the country's revised credit rating, which was given "junk" status by a ratings agency after Gordhan's dismissal.
Bank and resource stocks also succumbed to that pressure.
Mr. Zuma's fight for survival is inflicting heavy damage on South Africa's economy, with fresh predictions of near-zero growth after Fitch Ratings decided on Friday to follow S&P in downgrading the country's rating into the junk category.
Following the downgrades, J.P. Morgan said it would drop South Africa from its investment-grade emerging market bond indexes by late April.
Employees in the hospitality sector in Sandton use their lunch break to protest against Zuma.
The ruling African National Congress party has been hurt by scandals surrounding the president, and some party members have called for Zuma to quit.
Last week, Zuma replaced several high-profile ministers in a cabinet reshuffle which led to tumbling of the country's currency and stock markets, causing losses in millions of dollars.
Ethekwini mayor Zandile Gumede said the region would keep backing Zuma because "an attack on him is an attack on the ANC".
Separately, ruling party members assaulted several protesters participating in a march organized by the Democratic Alliance, South Africa's biggest opposition group.
"Let them wait for 2019 and we will take them on, but the ones that want to remove it undemocratically, MKMVA will rise up to the occasion".
Gauteng police spokesperson Mathapelo Peters said: "The police were forced to use rubber bullets, that's been communicated by the JMPD who were forced to restrain ANC supporters who were about to cross over to Mary Fitzgerald".
Mmusi Maimane, leader of the DA, led a crowd of about 10,000 people on a 1 km march in downtown Johannesburg. "I don't think it's the last time we're gonna see that", says Naidoo.
"The response from people has been absolutely remarkable", says Lawson Naidoo of Save South Africa - the campaign group leading the demonstrations. Some held placards saying "Fire Zuma".
A "holding hands" picket was due to take place in Cape Town, where motorists hooted in support of the march holding up South African flags. "ANC has not organized any march". And we need you now to help us fix this problem.
South Africa's Deputy-President Cyril Ramaphosa, among other senior ANC officials, called Zuma's decision "totally unacceptable", and the move appeared to have exposed deep divisions in the party, which has ruled the country virtually unchallenged since the end of white-minority rule-known as apartheid-in 1994.