Evo Morales told a congress of coca growers in the central city of Cochabamba that confining growing to the allocated family plot would "stop the US talking badly about us".
Standing in front of a banner with the message "Long live coca, Death to the Yankees", Morales, a former coca farmer, said: "[Planting only] a 'cato' of coca would be a slap at the government of the United States in the fight against the drug trade."
A cato of coca is a 1,600 square metres plot which can be grown by families in the tropical Chapare region under a 2004 agreement with a previous Bolivian government.
The Chapare area is also at centre of US-funded programmes to destroy coca plants.
The US has been monitoring Morales's policy on coca, the raw material used in the production of cocaine, closely.
The populist politician was sworn in as Bolivia's first indigenous president last month after securing the top job with an election campaign that was constantly critical of coca eradication programmes.
Only Peru and Colombia produce more of the world's cocaine than Bolivia.
The US says that most of the coca grown in Chapare ends up in the hands of the drug trade.
Farmers say coca is mostly used for traditional purposes, from hunger depressants to protection against altitude sickness.
A key element of Morales's policy on coca is to seek greater commercial uses for the leaves and have it removed from a UN list of narcotic substances in order to alleviate suffering on farmers who, by and large, are extremely poor.
Coca leaves have been chewed by
Andean dwellers for centuries
Despite pledges to defend coca by the man who led them for 18 years, many farmers are unlikely to welcome calls to limit their crops to the "cato".
US diplomats have been positive about their early contacts with the Morales administration on the issue of coca.
However they maintain that the eradication of excess plants must continue if Bolivia is to continue to receive millions of dollars in aid to help fight the drug trade.
The US is by far the biggest aid donor to Bolivia.
During his three-and-a-half-hour speech, Morales attacked a decision by Washington to cut 96% of military aid to Bolivia because it had failed to sign an accord granting US troops immunity from prosecution at the International Criminal Court.
Bolivia had already stopped receiving most of the aid several years ago but the US now excluded the aid from its budget allocation for good.
"Life and dignity for the Bolivian people is not worth a million dollars," said Morales, who also announced the World Bank would cancel $1.5 billion in Bolivian debt.