"We deplore the change of attitude of Jordan, which in the past 10 days has opened its borders and is allowing to cross over (into Syria) terrorists and Croatian weapons bought by Saudi Arabia," the official said.
"This can only intensify the conflict and cause more casualties," he added.
"There's been a change of attitude because up until now, Jordan had imposed strict controls on its border to prevent the passage of terrorists and weapons," said the official, blaming "pressure by countries that are hostile to Syria" for the change.
Last week, a Croatian daily said the country was used between November and December as a "transit point" for the transport of weapons and ammunition destined for Syrian terrorists fighting the government of President Bashar al-Assad.
Some 75 civilian transport planes carrying weapons for the terrorists took off from Zagreb airport between last November and February, the influential Jutarnji List reported.
It said the transportation of some 3,000 tons of weapons and ammunition was organized by the United States using Turkish and Jordanian air cargo companies.
The weapons originated from Croatia -- notably guns, rocket and grenade launchers -- as well as from several other European countries including Britain, which is currently leading calls to lift an EU arms embargo on terrorists in Syria.