Mr Tsvangira said the new government needed more time to fix the economy
Zimbabwe's Prime Minister, Morgan Tsvangirai, has said the new unity government is broke and can not meet trade union demands for higher wages.
Mr Tsvangirai said no state worker, including President Robert Mugabe, was earning more than $100 (£67) a month.
The unions have called for a monthly minimum of $450 and threatened to go on strike if their demand is not met.
But Mr Tsvangirai told a May Day rally in Harare that the government needed more time to fix the economy.
"This government is broke, and we are only able to pay the $100 allowance," Mr Tsvangirai told the crowds, adding that this would "graduate into a proper salary" when the situation improved and more people were paying tax.
"We have been in office for less than three months. I plead with you to please give us time," he said.
Mr Tsvangirai said the union demands "must be realistic" and take into account the government's financial situation and the underperformance of Zimbabwean industry.
"You supported us during hard times, we will pay you back," he said.
Earlier, Lovemore Matombo, the president of Zimbabwe's Congress of Trade Unions (ZCTU) told cheering workers that the unions were prepared to call a national strike, but he did not give a deadline.
Zimbabwe has asked for billions of dollars to help rebuild its economy, but Western countries have demanded broad reforms before restoring aid.