Carnival stock declined noticeably upon reporting "strong earnings" for the second quarter, most likely due to the company's cautious guidance for the rest of 2018, analysts say.

Infiniti Research analyst Assia Georgieva said investors expected a better third-quarter outlook than a 1.5% to 2.5% uptick in constant currency net revenue yields versus a year ago.

The company also lowered its EPS guidance for the quarter to $2.25