The letter states "immense respect" for Maduro's "valiantly fought" battle against the "decaying empire".
"Your cause is mine and has bound me like a magnetic field...but I have understood that you cannot turn water into wine or revive the dead.
"Please know, Mr President, that I am and will be at your side. But spiritually," the Ambassador said.
The Venezuelan embassy had been in arrears in payments of rent and staff salaries for several months due to the US sanctions and faced eviction, Rodriguez said at a press conference in Rome on May 8.
Eleven Italian employees have received no wages for four months, and two of them said they could no longer survive economically, Rodriguez said.
Maduro says the US is leading an "economic war" against his county. The sanctions have made it harder for the crisis-hit South American country to export oil but have also hampered imports of the diluents it needs to process its heavy crude oil.
Soon after a failed rebellion against Maduro led by opposition leader Juan Guaido at the end of April, the administration of US President Donald Trump on 10 May extended its Venezuela sanctions to the defence and security services sectors.
Since Maduro took office 2013, Venezuela's economy has halved in size amid hyperinflation and shortages of food, power, water, medicine and fuel, while several million people have left the country.
( With inputs from IANS )