HAVANA, Feb. 21 (Xinhua) -- A U.S. Congressional delegation on Wednesday urged President Donald Trump's administration to improve relations with Cuba amid tensions stemming from alleged "acoustic attacks" against U.S. diplomatic personnel in Cuba.

At a press conference after a three-day trip to Cuba where they met President Raul Castro and other government officials, the delegation, led by Democratic Senator Patrick Leahy, talked of the need to return to an era of engagement and cooperation.

"It's important for the Trump administration to stop falling back on Cold War policy that didn't make sense decades ago and makes less sense now," Senator Ron Wyden told reporters.

The delegation began their visit Monday by meeting with Cuban Foreign Ministry officials to talk about the alleged attacks suffered by U.S. diplomats in the Caribbean nation.

Over 20 U.S. diplomats suffered health problems between November 2016 and August 2017, which Washington called "acoustic attacks".

The incidents led to the partial closure of the U.S. embassy in Havana and a halt in issuing U.S. visas from there.

"We need to get back our embassy fully staffed ... There is no way we are going to have improved relations if we don't have the personnel here to do it," Leahy said.

The delegation said it was a mistake for the Trump administration to make political decisions based on an inconclusive investigation.

"I have no idea what happened to our diplomats here, U.S. agencies that are investigating this matter also don't seem to have a clue and we may never know. It was a mistake to cut back on our diplomatic personnel in Cuba," Representative Jim McGovern said.

The U.S. State Department issued a travel warning last year, telling Americans not to visit Cuba as some of the alleged attacks ostensibly occurred in hotels.

"It was a mistake to put out a travel advisory on Cuba warning Americans about their safety if they travel here. We feel safe in Cuba and I urge the Secretary of State to cancel this advisory," McGovern added.

The delegation's visit has been described as a "fact-finding trip" about the changes in Washington's policy toward Cuba.

"For too long our policy towards Cuba has been guided by paranoia and suspicion... it has resulted in a policy that I would characterize as stupid. We need to learn from our history, 50 years of hostility and estrangement was bad for the U.S. and Cuba," McGovern said.

Last year, Trump backpedaled on thawing ties with Havana by limiting trade with and travels to the Caribbean nation.

U.S. companies are forbidden from engaging in any type of commercial activities with over 180 Cuban companies associated with the Cuban armed forces. U.S. citizens are restricted from making individual trips to the island.

"Normal relations between the U.S. and Cuba are critically important, we need to move past any policies that have existed in the past, particularly those that have existed for 50 years and didn't bring about the change that any of us would like to see," Senator Gary Peters said.

Just before Trump assumed office, both nations signed over 20 cooperation agreements and bilateral meetings frequently took place.

However, the situation has changed dramatically since then and only a few exchanges on law enforcement, human and drug trafficking and security have taken place.