Interaction forces between a carbon nanotube (CNT) and an air-bubble in deionized water and methyl isobutyl carbinol (MIBC) solutions were measured by atomic force microscopy (AFM). The CNT terminated probe was brought into contact with the bubble at controlled velocities. The interaction forces sensed during the approach-retraction AFM cycle were recorded and analyzed. The repulsive steps followed by attractive jumps recorded in the approach force curves correspond to the multi-walled CNT changes in diameter along its length, an observation confirmed also by transmission electron microscopy (TEM). The long range of the attractive jumps in DI water exceeded the distance predicted by the DLVO theory modeled for two cases: the nanotube has a nanobubble attached to its end and the CNT is terminated with a graphene hemisphere. The diameter of the CNT end calculated from the pull-off forces was consistent with the TEM data. The pull-off forces measured in MIBC solutions decreased with increasing the surfactant concentration from 1 to 100mM, which suggests that MIBC is adsorbing on the interacting surfaces. These findings are expected to have direct implications on surface tension measurements and also on extending the understanding of nanoscale fundamental phenomena.