Venezuelan President Nicolas Maduro has called for a relationship with the United States based on diplomacy and an end to what he claims is a US plan to destabilise his government.
Mr Maduro was speaking to supporters in Caracas before meeting the Secretary General of the Union of South American Nations (Unasur), Ernesto Samper.
He later asked Mr Samper to mediate between Venezuela and the US.
The US imposed sanctions against Venezuelan officials in December.
They were aimed at those allegedly involved in suppressing the anti-government protests that shook Venezuela in the first six months of 2014.
On Monday, the US also imposed visa restrictions on unnamed Venezuelan officials it accuses of human rights violations and corruption.
Addressing crowds of supporters in the Venezuelan capital, Caracas, Mr Maduro called on the US president to “rectify and stop in time the coup plan (that would see) the destruction of Venezuela.
“President Obama, I say this with goodwill: We hope that you set a new and different tone with Venezuela.”
Relations between the US and Venezuela have been tense for many years. The two countries last had ambassadors in each other’s capitals in 2010.
Mr Maduro later told a news conference he had asked Unasur to “support the South American country” by mediating with the US.
For his part, Ernesto Samper said he would take Mr Maduro’s concerns to Unasur member states, adding that it was them who could decide on whether to take any action.
The South American union is based in the Ecuadorean capital, Quito, and is made up of 12 countries, including Venezuela.
Mr Maduro’s comments come days after he accused US Vice-President Joe Biden of plotting a coup against his left-wing government, an allegation that Mr Biden’s office called “baseless and patently false”.