A three-judge panel of the Second Circuit Court of Appeals said any attempt by the president to block critics responding to his tweets amounted to "unconstitutional viewpoint discrimination", the Efe news reported.
The appeals court, which is based in New York City, upheld a lower court ruling in the case of Knight First Amendment Institute v. Trump that the President's Twitter account constituted a "public forum."
The appeals court said its ruling was based on the principles in the US Constitution's First Amendment, which protects freedom of expression.
"We do conclude, however, that the First Amendment does not permit a public official who utilises a social media account for all manner of official purposes to exclude persons from an otherwise-open online dialogue because they expressed views with which the official disagrees," Judge Barrington D. Parker wrote in the decision.
The appeals panel said that the government and its officials had to allow differing points of view to be expressed.
"The public presentation of the Account and the webpage associated with it bear all the trappings of an official, state-run account," Parker said.
The Knight First Amendment Institute at New York's Columbia University filed a lawsuit in July 2017 against the President on behalf of seven Twitter users, alleging that he did not have the right to block individuals who posted critical comments in response to his tweets.
The plaintiffs argued that Trump used his personal Twitter account - @realDonaldTrump - to disseminate official government information, requiring him to provide access to everyone to the comment threads.
"Public officials' social media accounts are now among the most significant forums for discussion of government policy," Knight First Amendment Institute Executive Director Jameel Jaffer said.
"This decision will ensure that people aren't excluded from these forums simply because of their viewpoints, and that public officials aren't insulated from their constituents' criticism. The decision will help ensure the integrity and vitality of digital spaces that are increasingly important to our democracy," Jaffer said.
Trump has nearly 62 million Twitter followers and uses the social media platform regularly to announce new policies and weigh in on issues, providing fodder for the daily news cycle and receiving thousands of comments.
The President's attorneys had argued that the Twitter account was personal and not an official government account.
( With inputs from IANS )