The heightened security was implemented three days ago after Honduras' intelligence services received reports of a plan allegedly targeting those countries' embassies here and abroad, Security Minister Oscar Alvarez said.
"We are facing a state of preventative national alert, because our intelligence services report that al Qaeda foreigners have made offers for Hondurans to carry out sabotage both here and abroad," Alvarez said at a news conference.
Some Hondurans reportedly were offered money to carry out attacks, while others were approached on ideological grounds. Honduras has a tiny Islamic community.
"We believe that there are Hondurans who could accept these offers, some for money, and others because they believe in Islam," Alvarez said. "Our best agents are investigating the case and working out a strategy to prevent international terrorists from using Honduras as a base for training terrorists."
The purported al Qaeda plot was directly linked to the war in Iraq, which is why it targeted the United States, Britain and El Salvador, Alvarez said.
However, it was unclear why Spain was targeted since Madrid pulled its troops out of Iraq earlier this year.
Honduras withdrew its 370 soldiers in April.
"We are trying to avoid any problems," Alvarez said. "Starting three days ago, we have redoubled security measures at the embassies of those nations involved in Iraq. This situation will continue for the foreseeable future."
In July, Alvarez said a Saudi-born terror suspect sought by U.S. officials was spotted earlier this year at an Internet cafe in the Honduran capital before fleeing the country.
The man, Adnan G. El Shukrijumah, once lived in South Florida and is the subject of an FBI alert issued in 2003. The agency has asked law enforcement agencies and the public to be on the lookout for Shukrijumah on the grounds he may be plotting terrorist attacks against the United States or its interests abroad.
Shukrijumah, 29, apparently entered Honduras illegally from Nicaragua or Panama.
Alvarez refused to elaborate on the details surrounding the sighting of Shukrijumah and his subsequent disappearance.
However, Alvarez did not directly link Shukrijumah to the current alert, noting "his intention is to get into the United States" to commit attacks there.