HAVANA -- Cuba on Monday condemned a new measure by the United States to tighten its six-decade trade embargo against the island.

The measure essentially allows Cuban exiles in the United States to launch lawsuits against Cuban companies operating in properties that were nationalized or confiscated after its 1959 revolution.

"I strongly reject the US State Department announcement to allow lawsuits under Title III of the Helms-Burton Act against list of Cuban companies arbitrarily sanctioned by (Donald) Trump administration," tweeted Cuban Foreign Minister Bruno Rodriguez.

Starting March 19, US courts can process lawsuits against more than 200 Cuban businesses blacklisted by Washington for having ties with the island's military and intelligence services.

The US State Department on Monday granted a 30-day waiver for suits involving all other companies not blacklisted, which makes those companies and their investment on edge.

The "thirty-day waiver granted for all other cases is (an) unacceptable threat against the world," added Rodriguez.

If Title III was fully implemented, it would dampen the foreign investment Cuba seeks to develop its economy, and lead to years of litigation in US courts.

"The US State Department's decision is a hostile and irresponsible act that seeks to tighten the blockade and strangle the Cuban economy. It's a measure that has opposition in the world and the United States itself, whose business owners are against the embargo and favor trade with Cuba," said Rodriguez.

He sought to reassure foreign companies and investors that operate in the country, saying "you have the backing of Cuban laws, the international law and laws of your own countries."

Recent US presidents have suspended this section of the 1996 Helms-Burton Act, but Trump won office in part with the votes of Miami's Cuban expatriate community, by pledging to stiffen sanctions against the island.

US-Cuba relations have backslid since Trump took office, rolling back the detente initiated by his predecessor Barack Obama and reverting to Cold War rhetoric, but maintaining the restored diplomatic ties.