This comes as Britain said Tuesday that it would send military advisers to help organize the haphazard opposition forces with communications and logistics, but not with weapons or fighting.
The new tactics seem to have been spurred by the continued deadlock after two months of fighting between Gadhafi's army and rebel forces.
Over the weekend, the U.N. reached agreement with Gadhafi's government on carrying out aid operations in areas of Libya he controls.
A key destination for such aid would be the besieged rebel city of Misrata, where forces loyal to Gadhafi have been using mortar rounds and rocket-propelled grenades in their attacks.
The U.N. has said it has been promised access to Misrata, but has received no guarantees that fighting would be halted to allow aid in.
Explosions and gunfire were heard on Tuesday as rebels and troops clashed in central Misrata.
NATO has been unable to stop Gadhafi's forces with airstrikes alone. NATO officials said that they are having trouble destroying Gadhafi's mortars and rocket launchers from the air, for fear of inadvertently harming civilians.
The Associated Press contributed to this report.