Trump wrote that NATO without the United States is "a paper tiger" and complained that allies had refused to join efforts to secure shipping through the Strait of Hormuz.
"COWARDS, and we will REMEMBER!" he wrote, using capital letters for emphasis.
Trump has urged allies to help ensure safe passage through the strategic waterway, which Iran has blocked. About 20 percent of the world’s oil supply passes through the strait.
Most US allies were not consulted ahead of the military operation, according to the Reuters news agency.
The conflict, which began with US and Israeli strikes on Iran on February 28, has roiled global markets, killed thousands and displaced millions, it reported.
Trump said NATO countries were unwilling to join the fight against Iran but continued to complain about rising oil prices.
“Now that fight is militarily won, with very little danger for them, they complain about the high oil prices they are forced to pay, but don’t want to help open the Strait of Hormuz,” he wrote.
Earlier this week, Trump said most NATO allies had told Washington they did not want to get involved in the military operation, calling their stance a "very foolish mistake."
In comments to the Financial Times on Sunday, Trump warned NATO could face a "very bad future" if allies do not respond to his call to help secure the Strait of Hormuz.
The Strait of Hormuz is a vital global shipping route linking the Persian Gulf with international markets.
(gs)
Source: Reuters, IAR, PAP