"We see attempts to regroup among these terrorists," Putin told reporters in the Kyrgyz capital city of Bishkek on Saturday.
He said that the US cannot make a distinction between the so-called moderate opposition in Syria and Takfiri terrorists active in the Arab country.
"This is because of the difficulties they (the Americans) are facing... that they still can't separate the healthy part of the (Syrian) opposition from the semi-criminal,” he explained.
The Russian leader further stressed that his country is holding to its part of the Moscow-Washington mediated truce deal in Syria, with the Syrian army "fully abiding" by the cessation of hostilities.
Elsewhere in his comments, Putin expressed his "positive" attitude towards the ceasefire and voiced hope that the US would stick to its commitments on Syria, saying he believed that Moscow and Washington have a common goal of truce there.
"I would like us to be honest with one another... I don't really understand why we have to hide any agreements,” Putin said referring to the US failure to share with the United Nations documents outlining the joint Syria truce agreement.
Russia has repeatedly warned it could resume airstrikes on the so-called moderate militants unless Washington did more to distance them from extremists.
On September 9, Russia and the US agreed on a milestone deal on the crisis in Syria after hours of marathon talks in the Swiss city of Geneva.
The agreement, which came into effect on September 12, urges a nationwide cessation of hostilities in Syria and allows humanitarian access as well as joint Moscow-Washington attacks against terrorist groups, which are not covered by the deal, including Daesh and Jabhat Fateh al-Sham.
The seven-day truce is the second attempt this year by Russia and the US to bring an end to the Syria conflict, which started in March 2011.
Touching on the upcoming US presidential election, the Russian leader emphasized that Moscow would support any person in any country who "is friendly to us".
Back in July, the US accused Moscow of interfering in the country’s presidential election campaign after Washington blamed Russian hackers for a leak of US Democratic National Committee (DNC) emails. Moscow dismissed the allegations.
Republican presidential nominee Donald Trump has often expressed admiration for Putin, calling him a "strong leader." The Russian president has also praised the Republican nominee as "a very striking man" and "unquestionably talented.”
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