In an interview, the US president-elect said: “If Russia is really helping us, why would anybody have sanctions?”
Trump also said he was open to meeting Russian president Vladimir Putin after his inauguration.
Barack Obama imposed the sanctions in retaliation for alleged Russian interference in the US election.
Asked by the Wall Street Journal if he was committed to the “One China” policy, in which the US does not officially recognise Taiwan’s breakaway government, Trump said: “Everything is under negotiation.”
Meanwhile, the Senate Intelligence Committee says it will investigate possible contacts between Russia and the people associated with US political campaigns, in a broader investigation into Moscow’s alleged election meddling.
In a statement, Republican committee chairman Richard Burr and its top Democrat senator Mark Warner said the panel “will follow the intelligence where it leads”.
Burr and Warner said they would interview both senior Obama officials and those in the incoming Trump administration and subpoenas would be issued “if necessary to compel testimony”.
“We will conduct this inquiry expeditiously, and we will get it right,” they said.
A declassified intelligence report released last week said Putin ordered a hidden campaign to influence the election to favour Trump over Democrat Hillary Clinton - revelations that have rocked Washington.
Trump and his supporters have staunchly resisted the findings and Trump has fired a series of broadsides at US intelligence agencies, even though he will have to rely on their expertise to help him make major national security decisions once he takes over at the White House. He will be sworn in on Friday.
At a news conference last week, he speculated that US intelligence agencies might have leaked details about a classified briefing with him that included unsubstantiated allegations that Russia had collected compromising sexual and financial information about him. He said any such information was “all fake news. It’s phoney stuff. It didn’t happen.”
The bulk of the intelligence committee’s work will be done in secret, although the senators said they would hold open hearings when possible. “As the committee’s investigation progresses, we will keep Senate leadership, and the broader body, apprised of our findings,” they said.
Democrats and some Republicans have pressed for a select bi-partisan committee to conduct the investigation, but Republican leaders maintain that the existing committees are capable of handling the inquiries.
According to the committee’s statement, the inquiry will include a review of the intelligence that informed the declassified report about Russia’s interference in the election, “counterintelligence concerns” related to Russia and the election, and Russian cyber activity against the US during the election and more broadly.