Speaking alongside Latvian President Raimonds Vējonis, Poroshenko said: "Its a sunny day and I would say it reflects our relationship - with not a cloud in the sky," he joked.
"Latvia was one of the first countries that supported Ukraine's independence and well understands the situation today in Ukraine," and the "Russian occupation" in Donbas, Poroshenko said.
"We are very pleased to have Latvia supporting our territorial integrity and not accepting the annexation of Crimea," he added, suggesting that in order to defend against Russian aggression "We need to combine our strength - Ukraine and Latvia, Ukraine and Europe."
Poroshenko also thanked Latvia for the medical treatment it gives to injured Ukrainian combatants, saying such support "strengthens our fighting spirit".
For his part, President Vējonis said he hoped a visa-free regime between Ukraine and the countries of the EU's Schengen zone would become a reality "later this summer" as has already become the case with Georgia and would continue to offer "clear support for Ukraine's independence and its European integration path."
"Latvia understands the complexity of Ukraine's reform task and is ready too lend a helping hand. We already pass on our experience to Ukraine in regional reform, agriculture and anti-corruption," said Vējonis.
Both presidents expressed concern at reports Russia was continuing to assemble heavy weaponry close to the Ukrainian border with Vējonis saying Russia needed to engage constructively with the Minsk peace plan rather than continue "feeding the fire".
Poroshenko also said his country was fully justified in refusing entry to the singer due to compete on behalf of Russia at this year's Eurovision song contest because she had visited occupied Crimea without obtaining a special permit from Ukraine first.
"Russia is not interested in Eurovision but is interested in staging a provocation," Poroshenko said.
