Menendez's wrote a letter, as he said that he was concerned about a speech tomorrow at business summit by Donald J Trump Jr which may send a "mistaken message that he is speaking on behalf of Donald Trump".
The 40-year-old son of the US President is currently on a business trip India. He is executive vice president of the Trump Organization which is developing a number of high profile properties in various parts of the country.
"I expect that the US State Department, including US Embassy Delhi, will treat Mr Trump no differently than it would any other American individual visiting on private business, and will take every effort to avoid any perception of special treatment or a conflict of interest," he said as he listed a series of questions to Juster on the visit of the son of the US president.
In his letter, Menendez also raised concerns about his scheduled speech on Indo-Pacific relations at the Global Business Summit in Delhi on Friday.
"Given that Prime Minister Narendra Modi and multiple government ministers will speak at the same event, I am concerned that Mr Trump's speech will send the mistaken message that he is speaking on behalf of the President, the Administration or the United States government, not as a private individual, or that he is communicating official American policy," Menendez said.